Write a C program to reverse a string without using standard library function

Write a C program to reverse a string without using standard library function.

#include
#include
#include
void main() {
   char str[100], looper;
   int i, j = 0;
   clrscr();
   printf("Enter the string :\n");
   gets(str);
   i = 0;
   j = strlen(str) - 1;
 
   while (i < j) {
      looper = str[i];
      str[i] = str[j];
      str[j] = looper;
      i++;
      j--;
   }
 
   printf("The reverse string for entered string is :%s", str);
   getch();
}