2. Without strrev()

#include<stdio.h>

#include<string.h>

void stringReverse(char str[], int size){

int i = 0;

int j = size-1;

while(i<j){

char temp = str[i];

str[i] = str[j];

str[j] = temp;

i++;

j--;

}

}

int main(){

char str[] = "Learn Programming";

stringReverse(str,strlen(str));

printf("String After Reverse: %s",str);

return 0;

}

In the above program, the str is passed as argument to the function stringReverse along with its length. Length of the str is calculated using a library function strlen(str). Inside the function two index variable i and j is used and i is pointing at the start index and j is pointing at the last character. While loop will execute till the value of i-th index is less than j-th index and once both of the index is equal menas both the index is pointing to the middle of the character array. Inside the loop i is incremented and j is decremented by 1. Inside the while loop a temporary character variable temp is used to swap the i-th index character with the j-th index character of the array.

3. Reverse a string using function Recursion

#include<stdio.h>

#include<string.h>

void stringReverse(char str[], int i, int j){

if(i<j){

char temp = str[i];

str[i] = str[j];

str[j] = temp;

return stringReverse(str,i+1,j-1);

}

}

int main(){

char str[] = "Learn Programming";

stringReverse(str,0,strlen(str)-1);

printf("String After Reverse: %s",str);

}