Reverse String in C language

To invert a string, we need to exchange the last character with the first character, the second character with the last second character, etc., until we reach the middle of the string.

#include <stdio.h>
#include <string.h>
int main(void)
{
  //variable
  char str[100], tmp;
  int i, len, mid;
  
  //input
  printf("Enter a string: ");
  gets(str);
  
  //find number of characters
  len = strlen(str);
  mid = len/2;
  
  //reverse
  for (i = 0; i < mid; i++) {
    tmp = str[len - 1 - i];
    str[len - 1 - i] = str[i];
    str[i] = tmp;
  }
  
  //output
  printf("Reversed string: %s\n", str);
  printf("End of code\n");
  return 0;
}

output:

Enter a string: Hello World
Reversed string: dlroW olleH
End of code