⌨️

Section 1: Input & Output, Formatting

1 program

P–01 Declare variables of all C data types, take user input, print with alignment (left, right, width 10). Real numbers with 2 decimal places.

START
Declare variables: int i, float f, double d, char c, long l, short s
INPUT values for each variable from user
PRINT int with %-10d (left) and %10d (right)
PRINT float with %-10.2f and %10.2f
PRINT double with %-10.2lf and %10.2lf
PRINT char with %-10c and %10c
PRINT long with %-10ld and %10ld
PRINT short with %-10hd and %10hd
STOP

/* Program 1: All data types with formatting */
/* Author: [Your Name] | PGDCA-105 */
#include <stdio.h>

int main() {
    /* Declare all basic C data types */
    int i;
    float f;
    double d;
    char c;
    long l;
    short s;

    /* Input section */
    printf("Enter an integer: ");  scanf("%d", &i);
    printf("Enter a float: ");    scanf("%f", &f);
    printf("Enter a double: ");   scanf("%lf", &d);
    printf("Enter a char: ");     scanf(" %c", &c);
    printf("Enter a long: ");     scanf("%ld", &l);
    printf("Enter a short: ");    scanf("%hd", &s);

    /* Print with column width 10, left aligned */
    printf("\n--- LEFT ALIGNED (width 10) ---\n");
    printf("int    : %-10d\n", i);
    printf("float  : %-10.2f\n", f);
    printf("double : %-10.2lf\n", d);
    printf("char   : %-10c\n", c);
    printf("long   : %-10ld\n", l);
    printf("short  : %-10hd\n", s);

    /* Print with column width 10, right aligned */
    printf("\n--- RIGHT ALIGNED (width 10) ---\n");
    printf("int    : %10d\n", i);
    printf("float  : %10.2f\n", f);
    printf("double : %10.2lf\n", d);
    printf("char   : %10c\n", c);
    printf("long   : %10ld\n", l);
    printf("short  : %10hd\n", s);
    return 0;
}

Enter an integer: 42

Enter a float: 3.14

Enter a double: 2.71828

Enter a char: A

Enter a long: 123456789

Enter a short: 100

--- LEFT ALIGNED (width 10) ---

int : 42

float : 3.14

double : 2.72

char : A

long : 123456789

short : 100

--- RIGHT ALIGNED (width 10) ---

int : 42

float : 3.14

double : 2.72

char : A

long : 123456789

short : 100

🔄

Section 2: Loops & Decisions

Programs 2–8

P–02 Print all combinations of 1, 2, 3.

START
Use three nested loops: i, j, k from 1 to 3
FOR i = 1 to 3
FOR j = 1 to 3
FOR k = 1 to 3
IF i ≠ j AND j ≠ k AND i ≠ k
PRINT i, j, k
END IF
END FOR k
END FOR j
END FOR i
STOP

/* Program 2: All combinations of 1 2 3 */
#include <stdio.h>

int main() {
    int i, j, k, count = 0;
    printf("All combinations of 1 2 3:\n");
    /* Three nested loops for each position */
    for (i = 1; i <= 3; i++) {
        for (j = 1; j <= 3; j++) {
            for (k = 1; k <= 3; k++) {
                /* Ensure all three are distinct */
                if (i != j && j != k && i != k) {
                    printf("%d %d %d\n", i, j, k);
                    count++;
                }
            }
        }
    }
    printf("Total combinations: %d\n", count);
    return 0;
}

All combinations of 1 2 3:

1 2 3

1 3 2

2 1 3

2 3 1

3 1 2

3 2 1

Total combinations: 6

P–03 Generate patterns: (a) descending stars, (b) numbered triangle, (c) pyramid stars, (d) number pyramid.

START
/* Pattern A: Descending Stars */
FOR i = 5 downto 1: print (6-i) stars, newline
/* Pattern B: Numbered Triangle */
FOR i = 1 to 4: print numbers 1 to (i*(i+1)/2)
/* Pattern C: Star Pyramid */
FOR i = 1 to 5: print (5-i) spaces, then (2*i-1) stars
/* Pattern D: Number Pyramid */
FOR i = 1 to 4: print spaces, then i..1..i
STOP

/* Program 3: Pattern Generation */
#include <stdio.h>

int main() {
    int i, j, n = 5, num;

    /* Pattern (a): Descending star triangle */
    printf("Pattern A:\n");
    for (i = n; i >= 1; i--) {
        for (j = 1; j <= i; j++)
            printf("* ");
        printf("\n");
    }

    /* Pattern (b): Number staircase */
    printf("\nPattern B:\n");
    num = 1;
    for (i = 1; i <= 4; i++) {
        for (j = 1; j <= i * 2 - 1; j++)
            printf("%d ", num++);
        printf("\n");
    }

    /* Pattern (c): Star pyramid (centered) */
    printf("\nPattern C:\n");
    for (i = 1; i <= n; i++) {
        for (j = 1; j <= n - i; j++) printf(" ");
        for (j = 1; j <= 2 * i - 1; j++) printf("*");
        printf("\n");
    }

    /* Pattern (d): Number pyramid with mirror */
    printf("\nPattern D:\n");
    for (i = 1; i <= 4; i++) {
        for (j = 4; j > i; j--) printf(" ");
        for (j = i; j >= 1; j--) printf("%d ", j);
        for (j = 2; j <= i; j++) printf("%d ", j);
        printf("\n");
    }
    return 0;
}

Pattern A:

* * * * *

* * * *

* * *

* *

Pattern B:

2 3

4 5 6

7 8 9 10

Pattern C:

***

*****

*******

*********

Pattern D:

2 1 2

3 2 1 2 3

4 3 2 1 2 3 4

P–04 Menu-driven pattern program using switch: 11=for loop, 12=while loop, 13=do-while, 21=second pattern using for, etc.

START
INPUT choice (11, 12, 13, 21, 22, 23...)
SWITCH choice
CASE 11: Print Pattern 1 using for loop
CASE 12: Print Pattern 1 using while loop
CASE 13: Print Pattern 1 using do-while loop
CASE 21: Print Pattern 2 using for loop
DEFAULT: Invalid choice
END SWITCH
STOP

/* Program 4: Menu-driven pattern generator */
#include <stdio.h>

void pattern1_for() {
    int i, j;
    /* Descending stars using for */
    for (i = 5; i >= 1; i--) {
        for (j = 1; j <= i; j++) printf("* ");
        printf("\n");
    }
}
void pattern1_while() {
    int i = 5, j;
    /* Descending stars using while */
    while (i >= 1) {
        j = 1;
        while (j <= i) { printf("* "); j++; }
        printf("\n"); i--;
    }
}
void pattern1_dowhile() {
    int i = 5, j;
    /* Descending stars using do-while */
    do {
        j = 1;
        do { printf("* "); j++; } while (j <= i);
        printf("\n"); i--;
    } while (i >= 1);
}
void pattern2_for() {
    int i, j;
    /* Ascending stars using for */
    for (i = 1; i <= 5; i++) {
        for (j = 1; j <= i; j++) printf("* ");
        printf("\n");
    }
}
int main() {
    int choice;
    printf("11=Pat1/for 12=Pat1/while 13=Pat1/dowhile 21=Pat2/for: ");
    scanf("%d", &choice);
    switch (choice) {
        case 11: pattern1_for(); break;
        case 12: pattern1_while(); break;
        case 13: pattern1_dowhile(); break;
        case 21: pattern2_for(); break;
        default: printf("Invalid choice!\n");
    }
    return 0;
}

11=Pat1/for 12=Pat1/while 13=Pat1/dowhile 21=Pat2/for: 11

* * * * *

* * * *

* * *

* *

P–05 Display numbers 1 to 10 in octal, decimal, and hexadecimal.

START
Print header: Decimal | Octal | Hexadecimal
FOR i = 1 to 10
PRINT i with %d (decimal), %o (octal), %x (hex)
END FOR
STOP

/* Program 5: Numbers in Octal, Decimal, Hexadecimal */
#include <stdio.h>

int main() {
    int i;
    /* Print table header */
    printf("%-12s %-12s %-12s\n", "Decimal", "Octal", "Hexadecimal");
    printf("------------------------------------\n");
    /* Loop 1 to 10 */
    for (i = 1; i <= 10; i++) {
        printf("%-12d %-12o %-12x\n", i, i, i);
    }
    return 0;
}

Decimal Octal Hexadecimal

------------------------------------

1 1 1

2 2 2

8 10 8

9 11 9

10 12 a

P–06 Convert a number between any two number systems (user specifies input base and output base).

START
INPUT fromBase (2/8/10/16), number as string, toBase
Convert number from fromBase to decimal (intermediate)
FOR each digit: decimal = decimal * fromBase + digit_value
Convert decimal to toBase
WHILE decimal > 0: remainder = decimal % toBase; build result
PRINT result in toBase
STOP

/* Program 6: Number System Conversion */
#include <stdio.h>
#include <string.h>
#include <math.h>

/* Convert any base string to decimal */
long toDecimal(char *num, int base) {
    long dec = 0;
    int len = strlen(num);
    for (int i = 0; i < len; i++) {
        int d = (num[i] >= '0' && num[i] <= '9') ?
                  num[i] - '0' : num[i] - 'A' + 10;
        dec += d * (long)pow(base, len - i - 1);
    }
    return dec;
}
/* Convert decimal to any base */
void fromDecimal(long dec, int base) {
    char res[64]; int idx = 0;
    if (dec == 0) { printf("0"); return; }
    while (dec > 0) {
        int r = dec % base;
        res[idx++] = (r < 10) ? r + '0' : r - 10 + 'A';
        dec /= base;
    }
    for (int i = idx - 1; i >= 0; i--) printf("%c", res[i]);
}
int main() {
    char num[64];
    int fromBase, toBase;
    printf("Enter source base (2/8/10/16): "); scanf("%d", &fromBase);
    printf("Enter number: ");              scanf("%s", num);
    printf("Enter target base (2/8/10/16): "); scanf("%d", &toBase);
    long dec = toDecimal(num, fromBase);
    printf("Result (base %d): ", toBase);
    fromDecimal(dec, toBase);
    printf("\n");
    return 0;
}

Enter source base (2/8/10/16): 10

Enter number: 255

Enter target base (2/8/10/16): 16

Result (base 16): FF

P–07 Menu-driven: factorial, Fibonacci, sin series, exponential series, prime numbers, leap year using switch/loops/conditional.

START
INPUT choice (a/b/c/d/e/f)
SWITCH choice
CASE a: Factorial: result=1; FOR i=1 to n: result*=i
CASE b: Fibonacci: a=0,b=1; PRINT; FOR n-2 times: c=a+b; a=b; b=c
CASE c: Sin series: sin(x) = x - x³/3! + x⁵/5! - ...
CASE d: Exp series: e^x = 1 + x + x²/2! + x³/3! + ...
CASE e: Primes: check divisibility for each num
CASE f: Leap year: (y%4==0 && y%100!=0) || y%400==0
STOP

/* Program 7: Mathematical series menu */
#include <stdio.h>
#include <math.h>

int main() {
    int choice, n, i, isPrime;
    double x, term, sum, num1, num2, temp;
    long fact;

    printf("a)Factorial b)Fibonacci c)Sin d)Exp e)Primes f)LeapYear: ");
    scanf(" %c", (char*)&choice);

    switch(choice) {
        case 'a': /* Factorial */
            printf("Enter n: "); scanf("%d", &n);
            fact = 1;
            for(i = 1; i <= n; i++) fact *= i;
            printf("%d! = %ld\n", n, fact); break;
        case 'b': /* Fibonacci */
            printf("Enter n: "); scanf("%d", &n);
            num1 = 0; num2 = 1;
            printf("Fibonacci: 0 1 "); sum = 1;
            for(i = 2; i < n; i++) {
                temp = num1 + num2; printf("%.0f ", temp);
                sum += temp; num1 = num2; num2 = temp;
            }
            printf("\nSum = %.0f\n", sum); break;
        case 'c': /* Sin series */
            printf("Enter x(radians) and n terms: "); scanf("%lf %d", &x, &n);
            sum = 0; term = x; fact = 1;
            for(i = 1; i <= n; i++) {
                sum += term;
                term = -term * x * x / ((2*i) * (2*i+1));
            }
            printf("sin(%.2f) = %.6f\n", x, sum); break;
        case 'd': /* Exponential e^x */
            printf("Enter x and n terms: "); scanf("%lf %d", &x, &n);
            sum = 1; term = 1;
            for(i = 1; i <= n; i++) { term *= x/i; sum += term; }
            printf("e^%.2f = %.6f\n", x, sum); break;
        case 'e': /* Primes up to n */
            printf("Enter n: "); scanf("%d", &n);
            printf("Primes: ");
            for(i = 2; i <= n; i++) {
                isPrime = 1;
                for(int j = 2; j * j <= i; j++) if(i%j==0) { isPrime=0; break; }
                if(isPrime) printf("%d ", i);
            }
            printf("\n"); break;
        case 'f': /* Leap year */
            printf("Enter year: "); scanf("%d", &n);
            ((n%4==0 && n%100!=0) || n%400==0) ?
                printf("%d is a Leap Year\n", n) :
                printf("%d is NOT a Leap Year\n", n);
            break;
        default: printf("Invalid choice\n");
    }
    return 0;
}

a)Factorial b)Fibonacci c)Sin d)Exp e)Primes f)LeapYear: b

Enter n: 8

Fibonacci: 0 1 1 2 3 5 8 13

Sum = 33

P–08 Same as Program 7 but use library functions (pow, sin, exp, etc.).

START
Same menu as P7, but use <math.h> library functions
For Factorial: use tgamma(n+1)
For Sin series: use sin(x) directly
For Exp: use exp(x) directly
For prime: use sqrt(n) for optimization
STOP

/* Program 8: Using library functions */
#include <stdio.h>
#include <math.h>

int main() {
    int choice, n;
    double x;
    printf("a)Factorial b)Sin c)Exp d)Primes e)LeapYear: ");
    scanf(" %c", (char*)&choice);

    switch(choice) {
        case 'a': /* Factorial using tgamma (n! = tgamma(n+1)) */
            printf("Enter n: "); scanf("%d", &n);
            printf("%d! = %.0f\n", n, tgamma(n + 1)); break;
        case 'b': /* sin() from math.h */
            printf("Enter x (radians): "); scanf("%lf", &x);
            printf("sin(%.4f) = %.6f\n", x, sin(x)); break;
        case 'c': /* exp() from math.h */
            printf("Enter x: "); scanf("%lf", &x);
            printf("e^%.4f = %.6f\n", x, exp(x)); break;
        case 'd': /* Primes with sqrt optimization */
            printf("Enter n: "); scanf("%d", &n);
            printf("Primes up to %d: ", n);
            for(int i=2; i<=n; i++) {
                int p=1;
                for(int j=2; j<=(int)sqrt(i); j++) if(i%j==0){p=0;break;}
                if(p) printf("%d ",i);
            }
            printf("\n"); break;
        case 'e':
            printf("Enter year: "); scanf("%d", &n);
            printf("%d is%s a leap year\n", n, ((n%4==0&&n%100!=0)||n%400==0)?"":" NOT");
            break;
        default: printf("Invalid\n");
    }
    return 0;
}

a)Factorial b)Sin c)Exp d)Primes e)LeapYear: c

Enter x: 2

e^2.0000 = 7.389056

📦

Section 3: Arrays

Programs 9–13

P–09 String operations without library: reverse, count chars, copy, palindrome, vowels/consonants/punctuation, sort alphabets.

START
INPUT choice (a-f), string
CASE a – Reverse: i=0, j=len-1; WHILE i<j swap s[i],s[j]
CASE b – Count: count=0; WHILE s[i]!='\0' count++
CASE c – Copy: FOR each char: dest[i]=src[i]; dest[i]='\0'
CASE d – Palindrome: reverse copy; compare char by char
CASE e – Vowels/Consonants: check each char against aeiou
CASE f – Sort: bubble sort on char array
STOP

/* Program 9: String operations WITHOUT library */
#include <stdio.h>

int mylen(char s[]) { int i=0; while(s[i]) i++; return i; }

int main() {
    char s[100], dest[100], rev[100];
    int ch, i, j, len, vowels=0, cons=0, punc=0;
    printf("a)Rev b)Count c)Copy d)Palindrome e)Vowels f)Sort: ");
    scanf(" %c", (char*)&ch);
    printf("Enter string: "); scanf(" %[^\n]", s);
    len = mylen(s);

    switch(ch) {
        case 'a': /* Reverse */
            i=0; j=len-1;
            while(i<j){ char t=s[i]; s[i]=s[j]; s[j]=t; i++; j--; }
            printf("Reversed: %s\n", s); break;
        case 'b': /* Count characters */
            printf("Length: %d\n", len); break;
        case 'c': /* Copy string */
            for(i=0; i<=len; i++) dest[i]=s[i];
            printf("Copied: %s\n", dest); break;
        case 'd': /* Palindrome */
            for(i=0; i<len; i++) rev[i]=s[len-1-i]; rev[len]='\0';
            i=0; while(i<len && s[i]==rev[i]) i++;
            printf("%s %s palindrome\n", s, i==len?"IS":"is NOT"); break;
        case 'e': /* Count vowels, consonants, punctuation */
            for(i=0; i<len; i++) {
                char c = s[i]|32; /* lowercase */
                if(c=='a'||c=='e'||c=='i'||c=='o'||c=='u') vowels++;
                else if(c>='a' && c<='z') cons++;
                else if(s[i]!=' ') punc++;
            }
            printf("Vowels:%d Consonants:%d Punct:%d\n", vowels, cons, punc); break;
        case 'f': /* Sort alphabets (bubble sort) */
            for(i=0; i<len-1; i++)
                for(j=0; j<len-i-1; j++)
                    if(s[j]>s[j+1]){ char t=s[j]; s[j]=s[j+1]; s[j+1]=t; }
            printf("Sorted: %s\n", s); break;
        default: printf("Invalid\n");
    }
    return 0;
}

a)Rev b)Count c)Copy d)Palindrome e)Vowels f)Sort: d

Enter string: madam

madam IS palindrome

P–10 Integer array: sort elements, linear search, binary search using switch/if-else/loop.

START
INPUT n, array a[n]
CASE Sort: Bubble Sort – FOR i=0 to n-2: FOR j=0 to n-i-2: IF a[j]>a[j+1] swap
CASE Linear Search: FOR each element IF a[i]==key: found
CASE Binary Search: Sort first; low=0, high=n-1
WHILE low <= high: mid=(low+high)/2
IF a[mid]==key: found; ELIF a[mid]<key: low=mid+1; ELSE high=mid-1
STOP

/* Program 10: Array Sort and Search */
#include <stdio.h>

/* Bubble sort */
void bubbleSort(int a[], int n) {
    for(int i=0; i<n-1; i++)
        for(int j=0; j<n-i-1; j++)
            if(a[j]>a[j+1]){ int t=a[j]; a[j]=a[j+1]; a[j+1]=t; }
}
/* Linear search */
int linearSearch(int a[], int n, int key) {
    for(int i=0; i<n; i++) if(a[i]==key) return i;
    return -1;
}
/* Binary search */
int binarySearch(int a[], int n, int key) {
    int low=0, high=n-1;
    while(low<=high) {
        int mid=(low+high)/2;
        if(a[mid]==key) return mid;
        else if(a[mid]<key) low=mid+1;
        else high=mid-1;
    }
    return -1;
}
int main() {
    int a[50], n, ch, key, pos;
    printf("Enter n: "); scanf("%d", &n);
    printf("Enter %d elements: ", n);
    for(int i=0; i<n; i++) scanf("%d", &a[i]);
    printf("1)Sort 2)LinearSearch 3)BinarySearch: "); scanf("%d", &ch);
    switch(ch) {
        case 1: bubbleSort(a,n);
            printf("Sorted: ");
            for(int i=0; i<n; i++) printf("%d ",a[i]); printf("\n"); break;
        case 2: printf("Key: "); scanf("%d",&key);
            pos = linearSearch(a,n,key);
            pos!=-1 ? printf("Found at index %d\n",pos) : printf("Not found\n"); break;
        case 3: bubbleSort(a,n); printf("Key: "); scanf("%d",&key);
            pos = binarySearch(a,n,key);
            pos!=-1 ? printf("Found at index %d\n",pos) : printf("Not found\n"); break;
    }
    return 0;
}

Enter n: 5

Enter 5 elements: 64 34 25 12 22

1)Sort 2)LinearSearch 3)BinarySearch: 1

Sorted: 12 22 25 34 64

P–11 Read afternoon temperature for each day of a month; find average, hottest day, and coolest day.

START
Declare temp[31], n (days in month)
INPUT n
FOR i=0 to n-1: INPUT temp[i]
sum=0; max=temp[0]; min=temp[0]; hotDay=0; coolDay=0
FOR i=0 to n-1:
sum += temp[i]
IF temp[i] > max: max=temp[i]; hotDay=i+1
IF temp[i] < min: min=temp[i]; coolDay=i+1
avg = sum / n
PRINT avg, hotDay, max, coolDay, min
STOP

/* Program 11: Monthly Temperature Analysis */
#include <stdio.h>

int main() {
    float temp[31], sum = 0, avg, maxT, minT;
    int n, hotDay, coolDay;

    printf("Enter number of days in month: "); scanf("%d", &n);
    printf("Enter afternoon temperatures:\n");
    for(int i = 0; i < n; i++) {
        printf("Day %d: ", i+1); scanf("%f", &temp[i]);
    }

    /* Initialize max, min */
    maxT = minT = temp[0]; hotDay = coolDay = 1;

    for(int i = 0; i < n; i++) {
        sum += temp[i];
        if(temp[i] > maxT) { maxT = temp[i]; hotDay = i + 1; }
        if(temp[i] < minT) { minT = temp[i]; coolDay = i + 1; }
    }
    avg = sum / n;

    printf("\nMonthly Average Temp: %.2f°C\n", avg);
    printf("Hottest Day: Day %d (%.2f°C)\n", hotDay, maxT);
    printf("Coolest Day: Day %d (%.2f°C)\n", coolDay, minT);
    return 0;
}

Monthly Average Temp: 34.50°C

Hottest Day: Day 5 (42.00°C)

Coolest Day: Day 2 (28.00°C)

P–12 3×3 matrix operations: addition, subtraction, multiplication, inverse, transpose, diagonal sum.

START
INPUT matrix A[3][3] and B[3][3]
CASE Add: C[i][j] = A[i][j] + B[i][j]
CASE Sub: C[i][j] = A[i][j] - B[i][j]
CASE Mul: C[i][j] = Σ A[i][k]*B[k][j] for k=0..2
CASE Transpose: T[i][j] = A[j][i]
CASE Diagonal: sum = A[0][0]+A[1][1]+A[2][2]
CASE Inverse: det = a(ei-fh)-b(di-fg)+c(dh-eg); inv[i][j] = cofactor/det
STOP

/* Program 12: 3x3 Matrix Operations */
#include <stdio.h>

void printMatrix(float m[3][3]) {
    for(int i=0; i<3; i++) {
        for(int j=0; j<3; j++) printf("%8.2f", m[i][j]);
        printf("\n");
    }
}
int main() {
    float A[3][3], B[3][3], C[3][3];
    int ch;
    printf("Enter Matrix A (9 values):\n");
    for(int i=0;i<3;i++) for(int j=0;j<3;j++) scanf("%f",&A[i][j]);
    printf("Enter Matrix B (9 values):\n");
    for(int i=0;i<3;i++) for(int j=0;j<3;j++) scanf("%f",&B[i][j]);
    printf("1)Add 2)Sub 3)Mul 4)Transpose 5)Diagonal 6)Inverse: ");
    scanf("%d",&ch);
    switch(ch) {
        case 1: /* Addition */
            for(int i=0;i<3;i++) for(int j=0;j<3;j++) C[i][j]=A[i][j]+B[i][j];
            printf("A+B:\n"); printMatrix(C); break;
        case 2: /* Subtraction */
            for(int i=0;i<3;i++) for(int j=0;j<3;j++) C[i][j]=A[i][j]-B[i][j];
            printf("A-B:\n"); printMatrix(C); break;
        case 3: /* Multiplication */
            for(int i=0;i<3;i++) for(int j=0;j<3;j++) {
                C[i][j]=0;
                for(int k=0;k<3;k++) C[i][j]+=A[i][k]*B[k][j];
            }
            printf("A*B:\n"); printMatrix(C); break;
        case 4: /* Transpose */
            for(int i=0;i<3;i++) for(int j=0;j<3;j++) C[i][j]=A[j][i];
            printf("Transpose A:\n"); printMatrix(C); break;
        case 5: /* Diagonal Sum */
            printf("Diagonal sum = %.2f\n", A[0][0]+A[1][1]+A[2][2]); break;
        case 6: /* Inverse (3x3 cofactor method) */
            { float det = A[0][0]*(A[1][1]*A[2][2]-A[1][2]*A[2][1])
                       -A[0][1]*(A[1][0]*A[2][2]-A[1][2]*A[2][0])
                       +A[0][2]*(A[1][0]*A[2][1]-A[1][1]*A[2][0]);
              if(det==0) { printf("Singular matrix\n"); break; }
              C[0][0]=(A[1][1]*A[2][2]-A[1][2]*A[2][1])/det;
              C[0][1]=-(A[0][1]*A[2][2]-A[0][2]*A[2][1])/det;
              C[0][2]=(A[0][1]*A[1][2]-A[0][2]*A[1][1])/det;
              C[1][0]=-(A[1][0]*A[2][2]-A[1][2]*A[2][0])/det;
              C[1][1]=(A[0][0]*A[2][2]-A[0][2]*A[2][0])/det;
              C[1][2]=-(A[0][0]*A[1][2]-A[0][2]*A[1][0])/det;
              C[2][0]=(A[1][0]*A[2][1]-A[1][1]*A[2][0])/det;
              C[2][1]=-(A[0][0]*A[2][1]-A[0][1]*A[2][0])/det;
              C[2][2]=(A[0][0]*A[1][1]-A[0][1]*A[1][0])/det;
              printf("Inverse A:\n"); printMatrix(C); }
            break;
    }
    return 0;
}

1)Add 2)Sub 3)Mul 4)Transpose 5)Diagonal 6)Inverse: 3

A*B:

30.00 36.00 42.00

66.00 81.00 96.00

102.00 126.00 150.00

P–13 5×40 character array: sort strings, find largest/smallest string, search for string.

START
Declare str[5][40], n=5
INPUT 5 strings
CASE Sort: Bubble sort comparing strings (strcmp without library: char by char)
CASE Largest: Compare each string with max; if greater update max
CASE Smallest: Compare each string with min; if smaller update min
CASE Search: Compare key with each string; char by char
STOP

/* Program 13: 2D Character Array String Operations */
#include <stdio.h>

/* Custom strcmp: returns <0 if a<b, 0 if equal, >0 if a>b */
int mycmp(char *a, char *b) {
    while(*a && *a == *b) { a++; b++; }
    return *a - *b;
}
void mycpy(char *d, char *s) { while(*s) *d++ = *s++; *d = '\0'; }

int main() {
    char str[5][40], temp[40], key[40];
    int ch, found;

    printf("Enter 5 strings:\n");
    for(int i=0; i<5; i++) { printf("%d: ",i+1); scanf("%s",str[i]); }

    printf("1)Sort 2)Largest 3)Smallest 4)Search: "); scanf("%d",&ch);

    switch(ch) {
        case 1: /* Bubble sort strings */
            for(int i=0;i<4;i++) for(int j=0;j<4-i;j++)
                if(mycmp(str[j],str[j+1])>0) { mycpy(temp,str[j]); mycpy(str[j],str[j+1]); mycpy(str[j+1],temp); }
            printf("Sorted:\n"); for(int i=0;i<5;i++) printf("%s\n",str[i]); break;
        case 2: /* Largest string */
            mycpy(temp,str[0]);
            for(int i=1;i<5;i++) if(mycmp(str[i],temp)>0) mycpy(temp,str[i]);
            printf("Largest: %s\n",temp); break;
        case 3: /* Smallest string */
            mycpy(temp,str[0]);
            for(int i=1;i<5;i++) if(mycmp(str[i],temp)<0) mycpy(temp,str[i]);
            printf("Smallest: %s\n",temp); break;
        case 4: /* Search for string */
            printf("Enter search key: "); scanf("%s",key);
            found = -1;
            for(int i=0;i<5;i++) if(mycmp(str[i],key)==0) { found=i; break; }
            found!=-1 ? printf("Found at index %d\n",found) : printf("Not found\n"); break;
    }
    return 0;
}

Enter 5 strings:

1)Sort 2)Largest 3)Smallest 4)Search: 2

Largest: zebra

🔧

Section 4: Functions

Programs 14–19

P–14 Function power(a, b) to calculate a raised to b.

START
FUNCTION power(a, b): result=1
FOR i=1 to b: result = result * a
RETURN result
In main: INPUT a, b
PRINT power(a, b)
STOP

/* Program 14: Power function a^b */
#include <stdio.h>

/* Function to compute a raised to power b */
double power(double a, int b) {
    double result = 1.0;
    int neg = (b < 0);
    if(neg) b = -b;
    for(int i = 1; i <= b; i++)
        result *= a;
    return neg ? 1.0 / result : result;
}

int main() {
    double a;
    int b;
    printf("Enter base (a): ");  scanf("%lf", &a);
    printf("Enter exponent (b): "); scanf("%d", &b);
    printf("%.2f ^ %d = %.4f\n", a, b, power(a, b));
    return 0;
}

Enter base (a): 2

Enter exponent (b): 10

2.00 ^ 10 = 1024.0000

P–15 Demonstrate difference between static and auto variable.

START
Define function demo() with static int s=0 and auto int a=0
s++; a++; PRINT s and a
In main: Call demo() 3 times
Observe: static s retains value, auto a resets each call
STOP

/* Program 15: Static vs Auto variable */
#include <stdio.h>

void demo() {
    /* static: initialised once, retains value between calls */
    static int s = 0;
    /* auto (default): re-initialised every call */
    int a = 0;
    s++; a++;
    printf("static s = %d  |  auto a = %d\n", s, a);
}

int main() {
    printf("--- Calling demo() 3 times ---\n");
    demo(); /* Call 1 */
    demo(); /* Call 2 */
    demo(); /* Call 3 */
    return 0;
}

--- Calling demo() 3 times ---

static s = 1 | auto a = 1

static s = 2 | auto a = 1

static s = 3 | auto a = 1

P–16 Demonstrate difference between local and global variables.

START
Declare global variable x = 100
In function show(): PRINT global x
In function modify(): local x = 50; PRINT local x
In main: PRINT global x; call modify(); call show(); PRINT global x
Observe: local x in modify() doesn't affect global x
STOP

/* Program 16: Local vs Global Variable */
#include <stdio.h>

/* Global variable visible everywhere */
int x = 100;

void show() {
    /* Access global x */
    printf("Inside show(): global x = %d\n", x);
}
void modify() {
    /* Local x shadows global x */
    int x = 50;
    printf("Inside modify(): local x = %d\n", x);
}

int main() {
    printf("In main before calls: global x = %d\n", x);
    modify();
    show();
    printf("In main after calls: global x = %d\n", x);
    return 0;
}

In main before calls: global x = 100

Inside modify(): local x = 50

Inside show(): global x = 100

In main after calls: global x = 100

P–17 Functions: factorial, Fibonacci, Sin series, exponential series using switch/loops/functions.

START
Define separate functions: factorial(n), fibonacci(n), sinSeries(x,n), expSeries(x,n)
In main: INPUT choice; use switch to call appropriate function
factorial: returns long, iterative loop
fibonacci: prints series using loop
sinSeries: x - x³/3! + x⁵/5! - ... using loop
expSeries: 1 + x + x²/2! + ... using loop
STOP

/* Program 17: Functions for mathematical series */
#include <stdio.h>

long factorial(int n) {
    long f = 1; for(int i=2;i<=n;i++) f*=i; return f;
}
void fibonacci(int n) {
    double a=0,b=1,s=1,t;
    printf("Fib: 0 1 ");
    for(int i=2;i<n;i++){t=a+b;a=b;b=t;s+=t;printf("%.0f ",t);}
    printf("\nSum=%.0f\n",s);
}
void sinSeries(double x, int n) {
    double s=0,t=x; long f=1;
    for(int i=1;i<=n;i++) {
        s+=t;
        t=-t*x*x/((2*i)*(2*i+1));
    }
    printf("sin(%.4f) = %.6f\n",x,s);
}
void expSeries(double x, int n) {
    double s=1,t=1;
    for(int i=1;i<=n;i++) { t*=x/i; s+=t; }
    printf("e^%.4f = %.6f\n",x,s);
}
int main() {
    int ch, n; double x;
    printf("1)Fact 2)Fib 3)Sin 4)Exp: "); scanf("%d",&ch);
    switch(ch){
        case 1: printf("n: ");scanf("%d",&n);printf("%d!=%ld\n",n,factorial(n));break;
        case 2: printf("n: ");scanf("%d",&n);fibonacci(n);break;
        case 3: printf("x n: ");scanf("%lf %d",&x,&n);sinSeries(x,n);break;
        case 4: printf("x n: ");scanf("%lf %d",&x,&n);expSeries(x,n);break;
    }
    return 0;
}

1)Fact 2)Fib 3)Sin 4)Exp: 1

n: 6

6! = 720

P–18 Recursive functions: factorial, Fibonacci, sin/exp series, natural series.

START
recursive_factorial(n): IF n==0 RETURN 1 ELSE RETURN n*factorial(n-1)
recursive_fib(n): IF n<=1 RETURN n ELSE RETURN fib(n-1)+fib(n-2)
factorial_helper(n): returns n! = n * (n-1)!
sum_natural(n): IF n==0 RETURN 0 ELSE RETURN n + sum_natural(n-1)
STOP

/* Program 18: Recursive Functions */
#include <stdio.h>

/* Recursive factorial */
long rfact(int n) { return (n==0)?1:n*rfact(n-1); }

/* Recursive Fibonacci */
long rfib(int n) { return (n<=1)?n:rfib(n-1)+rfib(n-2); }

/* Recursive sum of natural numbers */
long rsum(int n) { return (n==0)?0:n+rsum(n-1); }

/* Recursive power a^b */
double rpow(double a, int b) {
    if(b==0) return 1;
    return a * rpow(a, b-1);
}

int main() {
    int ch, n; double a;
    printf("1)Fact 2)Fibonacci 3)SumNatural 4)Power: "); scanf("%d",&ch);
    switch(ch){
        case 1: printf("n: ");scanf("%d",&n);printf("%d!=%ld\n",n,rfact(n));break;
        case 2: printf("n: ");scanf("%d",&n);
            for(int i=0;i<n;i++) printf("%ld ",rfib(i)); printf("\n");break;
        case 3: printf("n: ");scanf("%d",&n);printf("Sum=%ld\n",rsum(n));break;
        case 4: printf("a b: ");scanf("%lf %d",&a,&n);
            printf("%.2f^%d=%.4f\n",a,n,rpow(a,n));break;
    }
    return 0;
}

1)Fact 2)Fibonacci 3)SumNatural 4)Power: 2

n: 8

0 1 1 2 3 5 8 13

P–19 Function to accept 10 characters and classify each as digit, uppercase, or lowercase letter.

START
FUNCTION classify(ch):
IF ch >= '0' && ch <= '9': RETURN "Digit"
ELIF ch >= 'A' && ch <= 'Z': RETURN "Uppercase"
ELIF ch >= 'a' && ch <= 'z': RETURN "Lowercase"
ELSE: RETURN "Special"
In main: FOR i=0 to 9: INPUT char c; PRINT classify(c)
STOP

/* Program 19: Character Classification */
#include <stdio.h>

char* classify(char c) {
    if(c >= '0' && c <= '9') return "Digit";
    if(c >= 'A' && c <= 'Z') return "Uppercase Letter";
    if(c >= 'a' && c <= 'z') return "Lowercase Letter";
    return "Special Character";
}

int main() {
    char c;
    printf("Enter 10 characters (one per line):\n");
    for(int i = 0; i < 10; i++) {
        printf("Char %2d: ", i+1); scanf(" %c", &c);
        printf("  '%c' -> %s\n", c, classify(c));
    }
    return 0;
}

Char 1: 'A' -> Uppercase Letter

Char 2: 'z' -> Lowercase Letter

Char 3: '5' -> Digit

Char 4: '#' -> Special Character

⚙️

Section 5: Array & Function

Programs 20–23 — Matrix & string operations using user-defined functions

P–20 Matrix (Function): multiply two matrices.

START
INPUT matrix A[3][3] and B[3][3]
CASE Add: C[i][j] = A[i][j] + B[i][j]
CASE Sub: C[i][j] = A[i][j] - B[i][j]
CASE Mul: C[i][j] = Σ A[i][k]*B[k][j] for k=0..2
CASE Transpose: T[i][j] = A[j][i]
CASE Diagonal: sum = A[0][0]+A[1][1]+A[2][2]
CASE Inverse: det = a(ei-fh)-b(di-fg)+c(dh-eg); inv[i][j] = cofactor/det
STOP

/* Program 20: Matrix (Function): multiply two matrices */
#include <stdio.h>

void printMatrix(float m[3][3]) {
    for(int i=0; i<3; i++) {
        for(int j=0; j<3; j++) printf("%8.2f", m[i][j]);
        printf("\n");
    }
}
int main() {
    float A[3][3], B[3][3], C[3][3];
    int ch;
    printf("Enter Matrix A (9 values):\n");
    for(int i=0;i<3;i++) for(int j=0;j<3;j++) scanf("%f",&A[i][j]);
    printf("Enter Matrix B (9 values):\n");
    for(int i=0;i<3;i++) for(int j=0;j<3;j++) scanf("%f",&B[i][j]);
    printf("1)Add 2)Sub 3)Mul 4)Transpose 5)Diagonal 6)Inverse: ");
    scanf("%d",&ch);
    switch(ch) {
        case 1: /* Addition */
            for(int i=0;i<3;i++) for(int j=0;j<3;j++) C[i][j]=A[i][j]+B[i][j];
            printf("A+B:\n"); printMatrix(C); break;
        case 2: /* Subtraction */
            for(int i=0;i<3;i++) for(int j=0;j<3;j++) C[i][j]=A[i][j]-B[i][j];
            printf("A-B:\n"); printMatrix(C); break;
        case 3: /* Multiplication */
            for(int i=0;i<3;i++) for(int j=0;j<3;j++) {
                C[i][j]=0;
                for(int k=0;k<3;k++) C[i][j]+=A[i][k]*B[k][j];
            }
            printf("A*B:\n"); printMatrix(C); break;
        case 4: /* Transpose */
            for(int i=0;i<3;i++) for(int j=0;j<3;j++) C[i][j]=A[j][i];
            printf("Transpose A:\n"); printMatrix(C); break;
        case 5: /* Diagonal Sum */
            printf("Diagonal sum = %.2f\n", A[0][0]+A[1][1]+A[2][2]); break;
        case 6: /* Inverse (3x3 cofactor method) */
            { float det = A[0][0]*(A[1][1]*A[2][2]-A[1][2]*A[2][1])
                       -A[0][1]*(A[1][0]*A[2][2]-A[1][2]*A[2][0])
                       +A[0][2]*(A[1][0]*A[2][1]-A[1][1]*A[2][0]);
              if(det==0) { printf("Singular matrix\n"); break; }
              C[0][0]=(A[1][1]*A[2][2]-A[1][2]*A[2][1])/det;
              C[0][1]=-(A[0][1]*A[2][2]-A[0][2]*A[2][1])/det;
              C[0][2]=(A[0][1]*A[1][2]-A[0][2]*A[1][1])/det;
              C[1][0]=-(A[1][0]*A[2][2]-A[1][2]*A[2][0])/det;
              C[1][1]=(A[0][0]*A[2][2]-A[0][2]*A[2][0])/det;
              C[1][2]=-(A[0][0]*A[1][2]-A[0][2]*A[1][0])/det;
              C[2][0]=(A[1][0]*A[2][1]-A[1][1]*A[2][0])/det;
              C[2][1]=-(A[0][0]*A[2][1]-A[0][1]*A[2][0])/det;
              C[2][2]=(A[0][0]*A[1][1]-A[0][1]*A[1][0])/det;
              printf("Inverse A:\n"); printMatrix(C); }
            break;
    }
    return 0;
}

1)Add 2)Sub 3)Mul 4)Transpose 5)Diagonal 6)Inverse: 3

A*B:

30.00 36.00 42.00

66.00 81.00 96.00

102.00 126.00 150.00

P–21 String (Function): count vowels, consonants, punctuation, sort alphabets.

START
INPUT string
CASE Count: count=0; WHILE s[i]!='\0' count++
CASE Copy: FOR each char: dest[i]=src[i]; dest[i]='\0'
CASE Palindrome: reverse copy; compare char by char
CASE Vowels/Consonants: check each char against aeiou
CASE Sort: bubble sort on char array
STOP

/* Program 21: String (Function): count vowels, consonants, punctuation, sort alphabets */
#include <stdio.h>

int mylen(char s[]) { int i=0; while(s[i]) i++; return i; }

int main() {
    char s[100], dest[100], rev[100];
    int ch, i, j, len, vowels=0, cons=0, punc=0;
    printf("a)Rev b)Count c)Copy d)Palindrome e)Vowels f)Sort: ");
    scanf(" %c", (char*)&ch);
    printf("Enter string: "); scanf(" %[^\n]", s);
    len = mylen(s);

    switch(ch) {
        case 'a': /* Reverse */
            i=0; j=len-1;
            while(i<j){ char t=s[i]; s[i]=s[j]; s[j]=t; i++; j--; }
            printf("Reversed: %s\n", s); break;
        case 'b': /* Count characters */
            printf("Length: %d\n", len); break;
        case 'c': /* Copy string */
            for(i=0; i<=len; i++) dest[i]=s[i];
            printf("Copied: %s\n", dest); break;
        case 'd': /* Palindrome */
            for(i=0; i<len; i++) rev[i]=s[len-1-i]; rev[len]='\0';
            i=0; while(i<len && s[i]==rev[i]) i++;
            printf("%s %s palindrome\n", s, i==len?"IS":"is NOT"); break;
        case 'e': /* Count vowels, consonants, punctuation */
            for(i=0; i<len; i++) {
                char c = s[i]|32; /* lowercase */
                if(c=='a'||c=='e'||c=='i'||c=='o'||c=='u') vowels++;
                else if(c>='a' && c<='z') cons++;
                else if(s[i]!=' ') punc++;
            }
            printf("Vowels:%d Consonants:%d Punct:%d\n", vowels, cons, punc); break;
        case 'f': /* Sort alphabets (bubble sort) */
            for(i=0; i<len-1; i++)
                for(j=0; j<len-i-1; j++)
                    if(s[j]>s[j+1]){ char t=s[j]; s[j]=s[j+1]; s[j+1]=t; }
            printf("Sorted: %s\n", s); break;
        default: printf("Invalid\n");
    }
    return 0;
}

a)Rev b)Count c)Copy d)Palindrome e)Vowels f)Sort: d

Enter string: madam

madam IS palindrome

P–22 Array (Function): sort elements, linear search, binary search using switch/if-else/loop.

START
INPUT n, array a[n]
CASE Sort: Bubble Sort – FOR i=0 to n-2: FOR j=0 to n-i-2: IF a[j]>a[j+1] swap
CASE Linear Search: FOR each element IF a[i]==key: found
CASE Binary Search: Sort first; low=0, high=n-1
WHILE low <= high: mid=(low+high)/2
IF a[mid]==key: found; ELIF a[mid]<key: low=mid+1; ELSE high=mid-1
STOP

/* Program 22: Array Sort and Search */
#include <stdio.h>

/* Bubble sort */
void bubbleSort(int a[], int n) {
    for(int i=0; i<n-1; i++)
        for(int j=0; j<n-i-1; j++)
            if(a[j]>a[j+1]){ int t=a[j]; a[j]=a[j+1]; a[j+1]=t; }
}
/* Linear search */
int linearSearch(int a[], int n, int key) {
    for(int i=0; i<n; i++) if(a[i]==key) return i;
    return -1;
}
/* Binary search */
int binarySearch(int a[], int n, int key) {
    int low=0, high=n-1;
    while(low<=high) {
        int mid=(low+high)/2;
        if(a[mid]==key) return mid;
        else if(a[mid]<key) low=mid+1;
        else high=mid-1;
    }
    return -1;
}
int main() {
    int a[50], n, ch, key, pos;
    printf("Enter n: "); scanf("%d", &n);
    printf("Enter %d elements: ", n);
    for(int i=0; i<n; i++) scanf("%d", &a[i]);
    printf("1)Sort 2)LinearSearch 3)BinarySearch: "); scanf("%d", &ch);
    switch(ch) {
        case 1: bubbleSort(a,n);
            printf("Sorted: ");
            for(int i=0; i<n; i++) printf("%d ",a[i]); printf("\n"); break;
        case 2: printf("Key: "); scanf("%d",&key);
            pos = linearSearch(a,n,key);
            pos!=-1 ? printf("Found at index %d\n",pos) : printf("Not found\n"); break;
        case 3: bubbleSort(a,n); printf("Key: "); scanf("%d",&key);
            pos = binarySearch(a,n,key);
            pos!=-1 ? printf("Found at index %d\n",pos) : printf("Not found\n"); break;
    }
    return 0;
}

Enter n: 5

Enter 5 elements: 64 34 25 12 22

1)Sort 2)LinearSearch 3)BinarySearch: 1

Sorted: 12 22 25 34 64

P–23 String Array (Function): sort, largest, smallest, search in a 5x40 char array.

START
INPUT 5 strings into arr[5][40]
MENU choice = 1-Sort, 2-Largest, 3-Smallest, 4-Search
IF choice == 1, sort strings and display
ELSE IF choice == 2, find largest string and display
ELSE IF choice == 3, find smallest string and display
ELSE IF choice == 4, search string and display result
STOP

/* Program 23: 5x40 string array operations */
#include <stdio.h>
#include <string.h>

void sortStrings(char arr[][40], int n) {
    for(int i=0; i<n-1; i++) {
        for(int j=0; j<n-i-1; j++) {
            if(strcmp(arr[j], arr[j+1]) > 0) {
                char temp[40];
                strcpy(temp, arr[j]);
                strcpy(arr[j], arr[j+1]);
                strcpy(arr[j+1], temp);
            }
        }
    }
}

void printStrings(char arr[][40], int n) {
    for(int i=0; i<n; i++) printf("%s\n", arr[i]);
}

int main() {
    char arr[5][40];
    int choice;
    printf("Enter 5 strings:\n");
    for(int i=0; i<5; i++) gets(arr[i]);
    printf("1)Sort 2)Largest 3)Smallest 4)Search: ");
    scanf("%d", &choice);
    getchar();
    switch(choice) {
        case 1:
            sortStrings(arr, 5);
            printStrings(arr, 5);
            break;
        case 2:
            char *largest = arr[0];
            for(int i=1; i<5; i++)
                if(strcmp(arr[i], largest) > 0) largest = arr[i];
            printf("Largest: %s\n", largest);
            break;
        case 3:
            char *smallest = arr[0];
            for(int i=1; i<5; i++)
                if(strcmp(arr[i], smallest) < 0) smallest = arr[i];
            printf("Smallest: %s\n", smallest);
            break;
        case 4:
            char key[40];
            printf("Search string: ");
            gets(key);
            int found=0;
            for(int i=0; i<5; i++)
                if(strcmp(arr[i], key)==0) { found = 1; break; }
            printf(found ? "Found\n" : "Not found\n");
            break;
    }
    return 0;
}

Enter 5 strings:

apple

orange

banana

grape

mango

1)Sort 2)Largest 3)Smallest 4)Search: 1

Sorted strings:

apple

banana

grape

mango

orange

📦

Section 6: Structures & Unions

Programs 24–27 — Struct Student, Struct Date/Employee, Complex numbers

P–24 Structure Student: roll, name, 3 subjects, marks, result.

START
Define STRUCT Student with: roll, name, sub1, sub2, sub3, maxmarks, minmarks, obtmarks
Declare struct variable s1
Read roll, name, subject names, marks
Calculate: total = sub1+sub2+sub3; avg = total/3; percent = (total/maxmarks)*100
Display: roll, name, subjects, marks, total, average, percentage, result (Pass/Fail)
STOP

/* Program 24: Structure Student */
#include <stdio.h>

struct Student {
    int roll;
    char name[50];
    char sub1[30], sub2[30], sub3[30];
    float mark1, mark2, mark3;
    float maxmarks, minmarks, obtmarks;
};

int main() {
    struct Student s;
    printf("Enter roll: "); scanf("%d", &s.roll);
    printf("Enter name: "); scanf("%s", s.name);
    printf("Enter 3 subject names: ");
    scanf("%s %s %s", s.sub1, s.sub2, s.sub3);
    printf("Enter 3 marks: ");
    scanf("%f %f %f", &s.mark1, &s.mark2, &s.mark3);
    printf("Enter max marks: "); scanf("%f", &s.maxmarks);
    printf("Enter min marks: "); scanf("%f", &s.minmarks);
    
    float total = s.mark1 + s.mark2 + s.mark3;
    float avg = total / 3;
    float percent = (total / s.maxmarks) * 100;
    
    printf("\n===== STUDENT RESULT =====\n");
    printf("Roll: %d\nName: %s\n", s.roll, s.name);
    printf("%s: %.1f\n%s: %.1f\n%s: %.1f\n", s.sub1, s.mark1, s.sub2, s.mark2, s.sub3, s.mark3);
    printf("Total: %.1f\nAverage: %.1f\nPercentage: %.2f%%\n", total, avg, percent);
    printf("Result: %s\n", percent >= 40 ? "PASS" : "FAIL");
    
    return 0;
}

Enter roll: 101

Enter name: John

Enter 3 subject names: Math English Science

Enter 3 marks: 85 75 90

Enter max marks: 300

Enter min marks: 120

===== STUDENT RESULT =====

Roll: 101

Name: John

Math: 85.0

English: 75.0

Science: 90.0

Total: 250.0

Average: 83.33

Percentage: 83.33%

Result: PASS

P–25 Nested Structure: Date (dd,mm,yy) inside Employee.

START
Define STRUCT Date with: dd, mm, yy
Define STRUCT Employee with: name, emp_id, doj (of type struct Date)
Declare struct Employee variable e1
Read employee name, id, date of joining (dd, mm, yy)
Display all employee details with formatted date
STOP

/* Program 25: Nested Structure - Date in Employee */
#include <stdio.h>

struct Date {
    int dd, mm, yy;
};

struct Employee {
    char name[50];
    int emp_id;
    struct Date doj;
};

int main() {
    struct Employee e;
    
    printf("Enter employee name: "); scanf("%s", e.name);
    printf("Enter employee id: "); scanf("%d", &e.emp_id);
    printf("Enter date of joining (dd mm yy): ");
    scanf("%d %d %d", &e.doj.dd, &e.doj.mm, &e.doj.yy);
    
    printf("\n===== EMPLOYEE DATA =====\n");
    printf("Name: %s\n", e.name);
    printf("Employee ID: %d\n", e.emp_id);
    printf("Date of Joining: %02d/%02d/%d\n", e.doj.dd, e.doj.mm, e.doj.yy);
    
    return 0;
}

Enter employee name: Alice

Enter employee id: 5001

Enter date of joining (dd mm yy): 15 3 2020

===== EMPLOYEE DATA =====

Name: Alice

Employee ID: 5001

Date of Joining: 15/03/2020

P–26 Array of Structures: 3 students, display all & specific results.

START
Define STRUCT Student (roll, name, marks)
Declare ARRAY of 3 struct Student
FOR i=0 to 2: Read roll, name, marks for each student
Display menu: 1-Show all results, 2-Search by roll
IF choice==1: Display all students' data
ELSE IF choice==2: Read roll number and display that student's data
STOP

/* Program 26: Array of Structures - Students */
#include <stdio.h>

struct Student {
    int roll;
    char name[50];
    float m1, m2, m3;
    float total, percent;
};

void displayAll(struct Student s[], int n) {
    for(int i=0; i<n; i++) {
        printf("\nRoll: %d | Name: %s | Total: %.1f | Percentage: %.1f%%\n", 
               s[i].roll, s[i].name, s[i].total, s[i].percent);
    }
}

void searchByRoll(struct Student s[], int n, int roll) {
    for(int i=0; i<n; i++) {
        if(s[i].roll == roll) {
            printf("\nRoll: %d\nName: %s\nMarks: %.1f, %.1f, %.1f\nTotal: %.1f\nPercentage: %.1f%%\n",
                   s[i].roll, s[i].name, s[i].m1, s[i].m2, s[i].m3, s[i].total, s[i].percent);
            return;
        }
    }
    printf("Student not found!\n");
}

int main() {
    struct Student s[3];
    
    printf("Enter data for 3 students:\n");
    for(int i=0; i<3; i++) {
        printf("\nStudent %d:\n", i+1);
        printf("Roll: "); scanf("%d", &s[i].roll);
        printf("Name: "); scanf("%s", s[i].name);
        printf("Marks: "); scanf("%f %f %f", &s[i].m1, &s[i].m2, &s[i].m3);
        s[i].total = s[i].m1 + s[i].m2 + s[i].m3;
        s[i].percent = (s[i].total / 300) * 100;
    }
    
    int choice;
    printf("\n1)Show All  2)Search: "); scanf("%d", &choice);
    if(choice == 1) displayAll(s, 3);
    else {
        int roll;
        printf("Enter roll to search: "); scanf("%d", &roll);
        searchByRoll(s, 3, roll);
    }
    
    return 0;
}

Enter data for 3 students:

Student 1: Roll: 101 Name: Alice Marks: 85 90 88

Student 2: Roll: 102 Name: Bob Marks: 75 80 82

Student 3: Roll: 103 Name: Carol Marks: 92 88 95

1)Show All 2)Search: 1

Roll: 101 | Name: Alice | Total: 263.0 | Percentage: 87.67%

Roll: 102 | Name: Bob | Total: 237.0 | Percentage: 79.00%

Roll: 103 | Name: Carol | Total: 275.0 | Percentage: 91.67%

P–27 Complex Numbers: add, subtract, multiply, divide using structures.

START
Define STRUCT complex with: real, imag
Read two complex numbers c1, c2
Menu: 1-Add, 2-Subtract, 3-Multiply, 4-Divide
FOR Add: result.real = c1.real + c2.real; result.imag = c1.imag + c2.imag
FOR Subtract: result.real = c1.real - c2.real; result.imag = c1.imag - c2.imag
FOR Multiply: (a+bi)*(c+di) = (ac-bd) + (ad+bc)i
FOR Divide: Use conjugate method
Display result in form: real +/- imag i
STOP

/* Program 27: Complex Numbers using Structures */
#include <stdio.h>

struct complex {
    float real, imag;
};

struct complex add(struct complex c1, struct complex c2) {
    struct complex res;
    res.real = c1.real + c2.real;
    res.imag = c1.imag + c2.imag;
    return res;
}

struct complex sub(struct complex c1, struct complex c2) {
    struct complex res;
    res.real = c1.real - c2.real;
    res.imag = c1.imag - c2.imag;
    return res;
}

struct complex mul(struct complex c1, struct complex c2) {
    struct complex res;
    res.real = (c1.real * c2.real) - (c1.imag * c2.imag);
    res.imag = (c1.real * c2.imag) + (c1.imag * c2.real);
    return res;
}

struct complex divd(struct complex c1, struct complex c2) {
    struct complex res;
    float denom = (c2.real * c2.real) + (c2.imag * c2.imag);
    res.real = ((c1.real * c2.real) + (c1.imag * c2.imag)) / denom;
    res.imag = ((c1.imag * c2.real) - (c1.real * c2.imag)) / denom;
    return res;
}

int main() {
    struct complex c1, c2, result;
    int op;
    
    printf("Enter c1 (real imag): "); scanf("%f %f", &c1.real, &c1.imag);
    printf("Enter c2 (real imag): "); scanf("%f %f", &c2.real, &c2.imag);
    printf("1)Add 2)Sub 3)Mul 4)Div: "); scanf("%d", &op);
    
    switch(op) {
        case 1: result = add(c1, c2); break;
        case 2: result = sub(c1, c2); break;
        case 3: result = mul(c1, c2); break;
        case 4: result = divd(c1, c2); break;
    }
    
    printf("\nResult: %.1f %c %.1fi\n", result.real, result.imag >= 0 ? '+' : '-', 
           result.imag >= 0 ? result.imag : -result.imag);
    
    return 0;
}

Enter c1 (real imag): 3 4

Enter c2 (real imag): 1 2

1)Add 2)Sub 3)Mul 4)Div: 1

Result: 4.0 + 6.0i

For Multiply (3+4i) * (1+2i):

Result: -5.0 + 10.0i

➤

Section 7: Pointers & Unions

Programs 28–42 — Union, Enum, Pointers, Pointer arithmetic, Linked Lists

P–28 Union Emp: test union with int, float, char array.

START
Define UNION Emp with: one int, one float, one char[20]
Declare union variable e
Assign value to e.i (int)
Display: e.i, size of union, address of e
Assign value to e.f (float) - overwrites e.i
Display: e.f, e.i (now corrupted)
Assign value to e.s (string) - overwrites e.f
Display: e.s, e.f (now corrupted)
STOP

/* Program 28: Union Test */
#include <stdio.h>

union Emp {
    int i;
    float f;
    char s[20];
};

int main() {
    union Emp e;
    
    printf("Size of union: %lu bytes\n", sizeof(e));
    
    e.i = 100;
    printf("\nAfter assigning int = 100:\n");
    printf("e.i = %d\n", e.i);
    printf("e.f = %f\n", e.f);
    printf("e.s = %s\n", e.s);
    
    e.f = 3.14;
    printf("\nAfter assigning float = 3.14:\n");
    printf("e.i = %d (overwritten)\n", e.i);
    printf("e.f = %f\n", e.f);
    
    strcpy(e.s, "Hello");
    printf("\nAfter assigning string = \"Hello\":\n");
    printf("e.i = %d (overwritten)\n", e.i);
    printf("e.f = %f (overwritten)\n", e.f);
    printf("e.s = %s\n", e.s);
    
    return 0;
}

Size of union: 20 bytes

After assigning int = 100:

e.i = 100

e.f = 0.000000

e.s =

After assigning float = 3.14:

e.i = 1074339225 (overwritten)

e.f = 3.140000

After assigning string = "Hello":

e.i = 1819042664 (overwritten)

e.f = 3.766226 (overwritten)

e.s = Hello

P–29 Enum DaysOfWeek: declare and test enum variable.

START
Define ENUM DaysOfWeek with: SUNDAY=0 to SATURDAY=6
Declare enum variable day
Assign values and display day names corresponding to enum values
Use switch to print day name for each enum value
STOP

/* Program 29: Enum Days of Week */
#include <stdio.h>

enum DaysOfWeek {
    SUNDAY = 0, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY
};

void printDay(enum DaysOfWeek day) {
    char *days[] = {"Sunday", "Monday", "Tuesday", "Wednesday", 
                      "Thursday", "Friday", "Saturday"};
    printf("%s\n", days[day]);
}

int main() {
    enum DaysOfWeek day;
    
    printf("Days of the week:\n");
    for(day = SUNDAY; day <= SATURDAY; day++) {
        printf("%d: ", day);
        printDay(day);
    }
    
    printf("\nEnter day number (0-6): ");
    int d; scanf("%d", &d);
    if(d >= 0 && d <= 6) {
        printf("Selected day: ");
        printDay((enum DaysOfWeek)d);
    }
    
    return 0;
}

Days of the week:

0: Sunday

1: Monday

2: Tuesday

3: Wednesday

4: Thursday

5: Friday

6: Saturday

Enter day number (0-6): 3

Selected day: Wednesday

P–30 Swap: call by value vs call by reference.

START
Read two numbers a, b
Display: Original a, b
Call swapByValue(a, b) - values copied, original unchanged
Display: After call by value (no change)
Call swapByReference(&a, &b) - addresses passed, original changed
Display: After call by reference (swapped)
STOP

/* Program 30: Call by Value vs Call by Reference */
#include <stdio.h>

void swapByValue(int x, int y) {
    int temp = x;
    x = y;
    y = temp;
    printf("  Inside swapByValue: x=%d, y=%d\n", x, y);
}

void swapByReference(int *x, int *y) {
    int temp = *x;
    *x = *y;
    *y = temp;
    printf("  Inside swapByReference: x=%d, y=%d\n", *x, *y);
}

int main() {
    int a, b;
    printf("Enter two numbers: ");
    scanf("%d %d", &a, &b);
    
    printf("\nOriginal: a=%d, b=%d\n", a, b);
    
    printf("\nCall by Value:\n");
    swapByValue(a, b);
    printf("  After return: a=%d, b=%d (no change)\n", a, b);
    
    printf("\nCall by Reference:\n");
    swapByReference(&a, &b);
    printf("  After return: a=%d, b=%d (swapped!)\n", a, b);
    
    return 0;
}

Enter two numbers: 10 20

Original: a=10, b=20

Call by Value:

Inside swapByValue: x=20, y=10

After return: a=10, b=20 (no change)

Call by Reference:

Inside swapByReference: x=20, y=10

After return: a=20, b=10 (swapped!)

P–43 Linked List: self-referential structure, create and print.

START
Define STRUCT Node with: data (int), *next pointer to Node
Create nodes dynamically using malloc
Link nodes: n1->next = n2, n2->next = n3, n3->next = NULL
Traverse list from head using while(temp != NULL)
Print each node's data
Free all allocated memory
STOP

/* Program 43: Linked List */
#include <stdio.h>
#include <stdlib.h>

struct Node {
    int data;
    struct Node *next;
};

struct Node* createNode(int val) {
    struct Node *newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = val;
    newNode->next = NULL;
    return newNode;
}

void printList(struct Node *head) {
    struct Node *temp = head;
    printf("Linked List: ");
    while(temp != NULL) {
        printf("%d -> ", temp->data);
        temp = temp->next;
    }
    printf("NULL\n");
}

int main() {
    struct Node *n1 = createNode(10);
    struct Node *n2 = createNode(20);
    struct Node *n3 = createNode(30);
    
    n1->next = n2;
    n2->next = n3;
    
    printList(n1);
    
    free(n1); free(n2); free(n3);
    
    return 0;
}

Linked List: 10 -> 20 -> 30 -> NULL

📄

Section 8: File Streams

Programs 44–47 — File I/O operations

P–44 Copy file removing extra spaces (from command line args).

START
Check command line: argc must be >= 3
Open source file argv[1] for reading
Open destination file argv[2] for writing
Read character by character from source
IF current char is space AND previous was space, skip
ELSE write character to destination
Close both files
STOP

/* Program 44: Copy file removing extra spaces */
#include <stdio.h>

int main(int argc, char *argv[]) {
    if(argc != 3) {
        printf("Usage: %s source.txt dest.txt\n", argv[0]);
        return 1;
    }
    
    FILE *src = fopen(argv[1], "r");
    FILE *dst = fopen(argv[2], "w");
    
    if(src == NULL || dst == NULL) {
        printf("Error opening file!\n");
        return 1;
    }
    
    int ch, prev_space = 0;
    while((fgetc(src)) != EOF) {
        if(ch == ' ') {
            if(!prev_space) fputc(ch, dst);
            prev_space = 1;
        } else {
            fputc(ch, dst);
            prev_space = 0;
        }
    }
    
    fclose(src);
    fclose(dst);
    printf("File copied successfully!\n");
    
    return 0;
}

$ gcc p44.c -o p44

$ ./p44 input.txt output.txt

File copied successfully!

P–45 Count all even numbers in a file "data".

START
Open file "data" for reading
Initialize count = 0
Read integers from file while not EOF
IF number % 2 == 0, increment count
Close file and display count
STOP

/* Program 45: Count even numbers in file */
#include <stdio.h>

int main() {
    FILE *fp = fopen("data.txt", "r");
    
    if(fp == NULL) {
        printf("Error: Cannot open file\n");
        return 1;
    }
    
    int num, even_count = 0;
    while(fscanf(fp, "%d", &num) != EOF) {
        if(num % 2 == 0) even_count++;
    }
    
    fclose(fp);
    printf("Total even numbers: %d\n", even_count);
    
    return 0;
}

File content: 10 15 20 25 30 35 40

Total even numbers: 4

P–46 Count tabs, newlines, characters, spaces in a file.

START
Open file for reading
Initialize: tabs=0, newlines=0, chars=0, spaces=0
Read each character using fgetc()
IF ch == '\t', increment tabs
ELSE IF ch == '\n', increment newlines
ELSE IF ch == ' ', increment spaces
ELSE increment chars
Display all counts
STOP

/* Program 46: Count tabs, newlines, chars, spaces */
#include <stdio.h>

int main() {
    FILE *fp = fopen("data.txt", "r");
    
    if(fp == NULL) {
        printf("Error: Cannot open file\n");
        return 1;
    }
    
    int tabs = 0, newlines = 0, chars = 0, spaces = 0;
    int ch;
    
    while((fgetc(fp)) != EOF) {
        if(ch == '\t') tabs++;
        else if(ch == '\n') newlines++;
        else if(ch == ' ') spaces++;
        else chars++;
    }
    
    fclose(fp);
    
    printf("===== FILE STATISTICS =====\n");
    printf("Tabs: %d\n", tabs);
    printf("Newlines: %d\n", newlines);
    printf("Spaces: %d\n", spaces);
    printf("Characters: %d\n", chars);
    
    return 0;
}

===== FILE STATISTICS =====

Tabs: 3

Newlines: 5

Spaces: 12

Characters: 42

P–47 Inventory: items with qty>5, total cost (from file).

START
Open inventory file for reading
Read: item_number, rate, quantity
Initialize: total_cost = 0
Display all items with quantity > 5
Calculate and add to total_cost = rate * quantity
Display total cost of entire inventory
Close file
STOP

/* Program 47: Inventory File Processing */
#include <stdio.h>

int main() {
    FILE *fp = fopen("inventory.txt", "r");
    
    if(fp == NULL) {
        printf("Error: Cannot open file\n");
        return 1;
    }
    
    int item_no, qty;
    float rate, total_cost = 0;
    
    printf("===== ITEMS WITH QUANTITY > 5 =====\n");
    printf("Item#\tRate\tQty\tCost\n");
    printf("-----\t-----\t---\t-----\n");
    
    float item_cost;
    while(fscanf(fp, "%d %f %d", &item_no, &rate, &qty) != EOF) {
        item_cost = rate * qty;
        total_cost += item_cost;
        
        if(qty > 5) {
            printf("%d\t%.2f\t%d\t%.2f\n", item_no, rate, qty, item_cost);
        }
    }
    
    printf("\n===== INVENTORY SUMMARY =====\n");
    printf("Total Cost: Rs. %.2f\n", total_cost);
    
    fclose(fp);
    return 0;
}

===== ITEMS WITH QUANTITY > 5 =====

Item# Rate Qty Cost

----- ----- --- -----

101 50.00 10 500.00

102 100.00 8 800.00

104 25.00 15 375.00

===== INVENTORY SUMMARY =====

Total Cost: Rs. 2250.00

Practical File
PGDCA-105

📋 Marks Distribution

Section 1: Input & Output, Formatting

Section 2: Loops & Decisions

Section 3: Arrays

Section 4: Functions

Section 5: Array & Function

Section 6: Structures & Unions

Section 7: Pointers & Unions

Section 8: File Streams

Component	Marks
Programme 1 (with flowchart & algorithm)	10
Programme 2 (with flowchart & algorithm)	10
Programme 3 (with flowchart & algorithm)	10
Viva-Voice	10
Practical Copy + Internal Record	10
Total	50

Practical FilePGDCA-105

📋 Marks Distribution

Section 1: Input & Output, Formatting

Section 2: Loops & Decisions

Section 3: Arrays

Section 4: Functions

Section 5: Array & Function

Section 6: Structures & Unions

Section 7: Pointers & Unions

Section 8: File Streams

Practical File
PGDCA-105