In this c program we are reversing a string without using library function( Strrev). we are using a temporary variable store for reversing the string.

  #include<stdio.h>
  #include<string.h>

int main() {
   char str[100], store ;
   int i, j = 0;

   printf("\nEnter the string :");
   gets(str);

   i = 0;
   j = strlen(str) - 1;

   while (i &lt; j) {
      store= str[i]; //the value at index i will be stored in store variable.
      str[i] = str[j];  // the value at index j will be stored in index i.

      str[j] = store;  // the value of store variable will be stored in index j
      i++;                // incrementing value of i by one.
      j--;                  // decrementing value of j by one.
   }

   printf("\nReverse string is :%s", str);
   return (0);
}

OUTPUT

Enter the string  : Suresh
Reverse string is :hseruS