#include <stdio.h>

void reverse(char *str){

    char * end1 = str;
    char tmp = 'c';
    if(str){
        while(*end1){
            ++end1;
        }
        --end1;

        while(str<end1){
            tmp=*str;
            *str=*end1;
            *end1=tmp;
            str++;
            end1--;
        }
    }
}

int main(void) {
	char x[] = "quick brown fox";
	reverse(x);
	printf("'%s'\n", x);
	return 0;
}