#include <stdio.h>
#include <string.h>

void back(char *c) {
    char s,x;
    char *e = c;
    char *p = c;
    while (*e++!='\0');
    e-=2;
    while (p!=e)  {
        s=*p;
        *p=*e;
        *e = s;
        p++;
        e--;
    }

}

int main() {
    char *c = "jadlsjdklsajdlasj";
    back(c);
}