#include <stdio.h>
#include <string.h>
char *_strrev(char *str) {
int len = strlen(str);
int left, right;
char temp;
left = 0;
right = len - 1;
while(left < right){
temp = str[left];
str[left] = str[right];
str[right] = temp;
left++;
right--;
}
return str;
}
int main () {
char str[] = {'a', 'b', 'c', 'd'};
_strrev(str);
printf("%s", str);
return 0;
}