C Programs: String, Array, Pointer & Control Examples
Section 1: String Programs
1. Reverse Individual Characters of a String
Language: C
#include <stdio.h>
#include <string.h>
int main() {
char str[100];
int length, i;
printf("Enter a string: ");
fgets(str, sizeof(str), stdin);
length = strlen(str);
if (length > 0 && str[length - 1] == '\n') {
str[length - 1] = '\0';
length--;
}
printf("The string in reverse order is: ");
for (i = length - 1; i >= 0; i--) {
printf("%c", str[i]);
}
printf("\n");
return 0;
}
2. Count Alphabets, Digits, and Special Characters
Language: C
#include <stdio.h>
#include <ctype.h>
#include <string.h>
int main() {
char str[100];
int alphabets = 0, digits = 0, specialCharacters = 0, i = 0;
printf("Enter a string: ");
fgets(str, sizeof(str), stdin);
int length = strlen(str);
if (length > 0 && str[length - 1] == '\n') {
str[length - 1] = '\0';
}
while (str[i] != '\0') {
unsigned char ch = (unsigned char)str[i];
if (isalpha(ch)) {
alphabets++;
} else if (isdigit(ch)) {
digits++;
} else {
specialCharacters++;
}
i++;
}
printf("Alphabets: %d\n", alphabets);
printf("Digits: %d\n", digits);
printf("Special Characters: %d\n", specialCharacters);
return 0;
}
3. Compare Two Strings
Language: C
#include <stdio.h>
#include <string.h>
int main() {
char str1[100], str2[100];
int i = 0, areEqual = 1;
printf("Enter first string: ");
scanf("%s", str1);
printf("Enter second string: ");
scanf("%s", str2);
while (str1[i] != '\0' && str2[i] != '\0') {
if (str1[i] != str2[i]) {
areEqual = 0;
break;
}
i++;
}
if (str1[i] == '\0' && str2[i] == '\0') {
printf("The strings are equal.\n");
} else {
printf("The strings are not equal.\n");
}
return 0;
}
4. Count Total Number of Vowels and Consonants
Language: C
#include <stdio.h>
#include <ctype.h>
#include <string.h>
int main() {
char str[100];
int vowels = 0, consonants = 0, i = 0;
printf("Enter a string: ");
fgets(str, sizeof(str), stdin);
int length = strlen(str);
if (length > 0 && str[length - 1] == '\n') {
str[length - 1] = '\0';
}
while (str[i] != '\0') {
char ch = tolower((unsigned char)str[i]);
if (isalpha((unsigned char)ch)) {
if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') {
vowels++;
} else {
consonants++;
}
}
i++;
}
printf("Vowels: %d\n", vowels);
printf("Consonants: %d\n", consonants);
return 0;
}
Section 2: DMS Programs
5. Grade Using Else-If Ladder
Language: C
#include <stdio.h>
int main() {
int marks;
printf("Enter the marks (0 - 100): ");
scanf("%d", &marks);
if (marks >= 90 && marks <= 100) {
printf("Grade: A\n");
} else if (marks >= 75 && marks < 90) {
printf("Grade: B\n");
} else if (marks >= 60 && marks < 75) {
printf("Grade: C\n");
} else if (marks >= 50 && marks < 60) {
printf("Grade: D\n");
} else if (marks >= 0 && marks < 50) {
printf("Grade: F (Fail)\n");
} else {
printf("Invalid marks entered! Please enter marks between 0 and 100.\n");
}
return 0;
}
6. Arithmetic Operators Using Switch-Case
Language: C
#include <stdio.h>
int main() {
int choice;
float num1, num2, result;
printf("Simple Arithmetic Operations Menu:\n");
printf("1. Addition\n");
printf("2. Subtraction\n");
printf("3. Multiplication\n");
printf("4. Division\n");
printf("5. Modulus\n");
printf("Enter your choice (1-5): ");
scanf("%d", &choice);
printf("Enter two numbers: ");
scanf("%f %f", &num1, &num2);
switch (choice) {
case 1:
result = num1 + num2;
printf("Result = %.2f\n", result);
break;
case 2:
result = num1 - num2;
printf("Result = %.2f\n", result);
break;
case 3:
result = num1 * num2;
printf("Result = %.2f\n", result);
break;
case 4:
if (num2 != 0.0f) {
printf("Result = %.2f\n", num1 / num2);
} else {
printf("Error: Division by zero is not allowed.\n");
}
break;
case 5:
if ((int)num2 != 0) {
printf("Result = %d\n", (int)num1 % (int)num2);
} else {
printf("Error: Modulus by zero is not allowed.\n");
}
break;
default:
printf("Invalid choice! Please choose between 1 and 5.\n");
}
return 0;
}
7. Positive / Negative and Even / Odd
Language: C
#include <stdio.h>
int main() {
int choice, num;
printf("Enter a number: ");
scanf("%d", &num);
printf("\nMenu:\n");
printf("1. Check Positive or Negative\n");
printf("2. Check Even or Odd\n");
printf("Enter your choice (1-2): ");
scanf("%d", &choice);
switch (choice) {
case 1:
if (num >= 0)
printf("%d is Positive.\n", num);
else
printf("%d is Negative.\n", num);
break;
case 2:
if (num % 2 == 0)
printf("%d is Even.\n", num);
else
printf("%d is Odd.\n", num);
break;
default:
printf("Invalid choice! Please choose 1 or 2.\n");
}
return 0;
}
Section 3: Array Programs
8. Display Largest and Smallest Element in an Array
Language: C
#include <stdio.h>
int main() {
int n, i, choice;
int largest, smallest;
printf("Enter the number of elements in the array: ");
scanf("%d", &n);
int arr[n];
printf("Enter the elements of the array:\n");
for (i = 0; i < n; i++) {
scanf("%d", &arr[i]);
}
do {
printf("\nMenu:\n");
printf("1. Find the largest element\n");
printf("2. Find the smallest element\n");
printf("3. Exit\n");
printf("Enter your choice: ");
scanf("%d", &choice);
switch (choice) {
case 1:
largest = arr[0];
for (i = 1; i < n; i++) {
if (arr[i] > largest) {
largest = arr[i];
}
}
printf("The largest element is: %d\n", largest);
break;
case 2:
smallest = arr[0];
for (i = 1; i < n; i++) {
if (arr[i] < smallest) {
smallest = arr[i];
}
}
printf("The smallest element is: %d\n", smallest);
break;
case 3:
printf("Exiting the program.\n");
break;
default:
printf("Invalid choice. Please try again.\n");
}
} while (choice != 3);
return 0;
}
9. Addition of Two Matrices
Language: C
#include <stdio.h>
int main() {
int rows, cols, i, j;
printf("Enter the number of rows: ");
scanf("%d", &rows);
printf("Enter the number of columns: ");
scanf("%d", &cols);
int mat1[rows][cols], mat2[rows][cols], result[rows][cols];
printf("Enter the elements of the first matrix:\n");
for (i = 0; i < rows; i++) {
for (j = 0; j < cols; j++) {
scanf("%d", &mat1[i][j]);
}
}
printf("Enter the elements of the second matrix:\n");
for (i = 0; i < rows; i++) {
for (j = 0; j < cols; j++) {
scanf("%d", &mat2[i][j]);
}
}
for (i = 0; i < rows; i++) {
for (j = 0; j < cols; j++) {
result[i][j] = mat1[i][j] + mat2[i][j];
}
}
printf("Resulting matrix after addition:\n");
for (i = 0; i < rows; i++) {
for (j = 0; j < cols; j++) {
printf("%d ", result[i][j]);
}
printf("\n");
}
return 0;
}
10. Sum of Principal Diagonal Elements
Language: C
#include <stdio.h>
int main() {
int n, i, j, sum = 0;
printf("Enter the size of the square matrix: ");
scanf("%d", &n);
int matrix[n][n];
printf("Enter the elements of the matrix:\n");
for (i = 0; i < n; i++) {
for (j = 0; j < n; j++) {
scanf("%d", &matrix[i][j]);
}
}
for (i = 0; i < n; i++) {
sum += matrix[i][i];
}
printf("The sum of the principal diagonal elements is: %d\n", sum);
return 0;
}
Section 4: Pointer & Structure Programs
11. Store and Print Student Details Using Structure
Language: C
#include <stdio.h>
struct Student {
char name[50];
int roll;
float marks;
};
int main() {
struct Student s;
printf("Enter student name: ");
scanf("%49s", s.name);
printf("Enter roll number: ");
scanf("%d", &s.roll);
printf("Enter marks: ");
scanf("%f", &s.marks);
printf("\nStudent Details:\n");
printf("Name: %s\n", s.name);
printf("Roll Number: %d\n", s.roll);
printf("Marks: %.2f\n", s.marks);
return 0;
}
12. Swap Two Numbers Using Pointers
Language: C
#include <stdio.h>
void swap(int *a, int *b) {
int temp = *a;
*a = *b;
*b = temp;
}
int main() {
int x, y;
printf("Enter two numbers: ");
scanf("%d %d", &x, &y);
printf("Before swapping: x = %d, y = %d\n", x, y);
swap(&x, &y);
printf("After swapping: x = %d, y = %d\n", x, y);
return 0;
}