C语言简单strcat和strcmp的实现

对于C标准库中的字符串处理函数应该平常用的比较多；简单实现strcat和strcmp

_strcpy:

char *_strcpy(char *dest, char *src)
{
    char *buf = dest;
    while((*dest++ = *src++))
        ;
    return buf;
}

_strcmp:

int _strcmp(char *str1, char *str2)
{
    if(str1 == NULL || str2 == NULL)
        return -1;
    while(*str1 == *str2)
    {
        if(*str1 == '')  // *str1 == 0
            return 0;
        str1++;
        str2++;
    }
    return *str1 - *str2;
}

_strlen:

int _strlen(char *str)
{
    int i= 0;
    while(*str)
    {
        i++;
        str++;
    }
    return i;
}

_strcat:

char *_strcat(char *dest, char *src)
{
    if(sizeof(dest) - _strlen(dest) < _strlen(src))
    {
        printf("!!alert : not enough space of dest for src !
");
        return dest;
    }
    char *buf = dest;
    while(*dest)
        dest++;
    _strcpy(dest, src);
    return buf;
}

Source Code : https://github.com/huaixzk/_strs.so