To Reverse a string using library function

Aim:
To Reverse a string using library functions

Program:

Code-1:
#include< stdio.h>
#include<string.h>
void main ()
  {
    char str[80];
    int i;
printf("Enter a String:");
gets(str);
printf("\nReverse string is:");
   for(i=strlen(str)-1;i>0;i--)
      printf("%c",str[i]);
  }

Output:
Enter a string: hahaha
Revere string is: ahahah

Code-2:
#include< stdio.h>
#include<string.h>
void main ()
  {
    char str[80];
printf("Enter a String:");
gets(str);
  printf("%s\n",str);
printf("Reverse string is:%s",strrev(str));
  }

Output:
Enter a string: cprogram
Reverse string is: margorpc