Reverse string

#include <string.h>
void reverse(char a[])
{
         int i, j,
         int j = strlen(a) -1 ;
         for (i=0; i<j; i++, j--)
         {
                  c = a[i] ;
                  a[i] = a[j] ;
                  a[j] = c ;
        }
}