/* Input a string and print its reverse
   Emad Arasteh
   November 29, 2018
*/

#include <stdio.h>

#define MAX_SLEN 128

unsigned int string_len(char[]);
void reverse(char[], unsigned int);

unsigned int string_len(char str[])
{
  char* p = str;
  unsigned int len = 0;

  while(*p++) {
    len++;
  }

  return len;
}

void reverse(char str[], unsigned int len) {
  int i;

  for(i = 0; i < len/2; i++) {
    char t = str[i];
    str[i] = str[len-1-i];
    str[len-1-i] = t;
  }
}

int main() {

  char str[MAX_SLEN];
  unsigned int len;

  printf("Input a string: ");
  scanf("%127s", str);

  len = string_len(str);
  reverse(str, len);

  printf("The reverse is: %s\n", str);

  return 0;
}