Reverse a String
Explanation: This program reverses a given string.
Code:
#include <stdio.h>
#include <string.h>
int main() {
char str[100];
printf("Enter a string: ");
gets(str);
strrev(str);
printf("Reversed string: %s\n", str);
return 0;
}
output:
Enter a string: hello
Reversed string: olleh
Check Prime Number
Explanation: This program checks if a given number is prime.
Code:
#include <stdio.h>
#include <math.h>
int isPrime(int num) {
if (num <= 1) return 0;
for (int i = 2; i <= sqrt(num); i++) {
if (num % i == 0) return 0;
}
return 1;
}
int main() {
int num;
printf("Enter a number: ");
scanf("%d", &num);
if (isPrime(num)) {
printf("%d is a prime number.\n", num);
} else {
printf("%d is not a prime number.\n", num);
}
return 0;
}
output:
Enter a number: 29
29 is a prime number.
Sum of Array Elements
Explanation: This program calculates the sum of elements in an array.
Code:
#include <stdio.h>
int main() {
int n;
printf("Enter the number of elements: ");
scanf("%d", &n);
int arr[n], sum = 0;
printf("Enter the elements of the array:\n");
for (int i = 0; i < n; i++) {
scanf("%d", &arr[i]);
sum += arr[i];
}
printf("The sum of the array elements is: %d\n", sum);
return 0;
}
output:
Enter the number of elements: 5
Enter the elements of the array:
1 2 3 4 5
The sum of the array elements is: 15
Factorial of a Number
Explanation: This program calculates the factorial of a given number.
Code:
#include <stdio.h>
int factorial(int num) {
if (num == 0 || num == 1) return 1;
return num * factorial(num - 1);
}
int main() {
int num;
printf("Enter a number: ");
scanf("%d", &num);
printf("The factorial of %d is: %d\n", num, factorial(num));
return 0;
}
output:
Enter a number: 5
The factorial of 5 is: 120
Check Palindrome Number
Explanation: This program checks if a given number is a palindrome.
Code:
#include <stdio.h>
void insertionSort(int arr[], int n) {
for (int i = 1; i < n; i++) {
int key = arr[i];
int j = i - 1;
while (j >= 0 && arr[j] > key) {
arr[j + 1] = arr[j];
j--;
}
arr[j + 1] = key;
}
}
int main() {
int n;
printf("Enter the number of elements: ");
scanf("%d", &n);
int arr[n];
printf("Enter the elements of the array:\n");
for (int i = 0; i < n; i++) {
scanf("%d", &arr[i]);
}
insertionSort(arr, n);
printf("Sorted array: ");
for (int i = 0; i < n; i++) {
printf("%d ", arr[i]);
}
printf("\n");
return 0;
}
output:
Enter the number of elements: 5
Enter the elements of the array:
5 2 9 1 5
Sorted array: 1 2 5 5 9
Binary Search
Explanation: This program implements binary search on a sorted array.
Code:
#include <stdio.h>
int binarySearch(int arr[], int size, int key) {
int low = 0, high = size - 1;
while (low <= high) {
int mid = low + (high - low) / 2;
if (arr[mid] == key) return mid;
if (arr[mid] < key) low = mid + 1;
else high = mid - 1;
}
return -1;
}
int main() {
int n, key;
printf("Enter the number of elements: ");
scanf("%d", &n);
int arr[n];
printf("Enter the sorted elements of the array:\n");
for (int i = 0; i < n; i++) {
scanf("%d", &arr[i]);
}
printf("Enter the key to search: ");
scanf("%d", &key);
int result = binarySearch(arr, n, key);
if (result != -1) {
printf("Element found at index: %d\n", result);
} else {
printf("Element not found.\n");
}
return 0;
}
output:
Enter the number of elements: 5
Enter the sorted elements of the array:
1 3 5 7 9
Enter the key to search: 7
Element found at index: 3
