字符串相关

记录一些与字符串相关的算法

strcmp

/*
字符串比较函数
s1 = s2: return 0;
s1 > s2: return 1;
s1 < s2: return -1;
 */
int strcmp(const char* s1, const char* s2){
    if(NULL == s1 || NULL == s2)
        throw "Invalid arguments";

    int ret = 0;
    while(!(ret=*s1-*s2) && *s1 && *s2){
        ++s1;
        ++s2;
    }
    if(ret > 0){
        ret = 1;
    }else if(ret < 0){
        ret = -1
    }

    return ret;
}

strcpy

/*
把从s2地址开始且含有'\0'结束符的字符串复制到以s1开始的地址空间
 */
char* strcpy(char* s1, const char* s2){
    if(NULL == s1 || NULL == s2)
        throw "Invalid arguments";

    char* p = s1;
    while((*s1++ = *s2++) != '\0');

    return p;
}