Reverse an input character string

<pre name="code" class="cpp">#include<stdio.h>#include<string.h>int main(){  char str[50];  int lenth,i;  printf("Please input a character string:\n");  gets(a);  l = strlen(a);  for (p = &a[l-1]; p >= a; p--)    {      printf("%c",*p);    }  printf("\n");  for (i = l - 1; i >= 0; i--)   {    printf("%c",a[i]);   }   printf("\n");  return 0;}

Input: 

Please input a character string:

I am great!

Output: 
!taerg ma I