undefined reference to strrev 解決方案

其實

strrev

這個函數不是系統庫裡面的，編譯器不自帶，要是出現

undefined reference to strrev

這個報錯怎麼辦呢，那就自己寫一個喽，😀

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


char* strrev(char *str)
{
    char *p1, *p2;
    if (! str || ! *str)
        return str;
    for (p1 = str, p2 = str + strlen(str) - 1; p2 > p1; ++p1, --p2)
    {
        *p1 ^= *p2;
        *p2 ^= *p1;
        *p1 ^= *p2;
    }
    return str;
}

int main ()
{

    char test[10] = "88090";
    char *r2 = strrev(test);
    int tmp = atoi(r2);
    printf("r2 is %s\n", r2);
    printf("tmp is %d\n", tmp);
    return 0;    
}
/*
output:
r2 is 09088
tmp is 9088
*/