习题8-5 使用函数实现字符串部分复制

void strmcpy(char *t, int m, char *s)
{
    int len = 0; //计算字符串t的长度
    char *p = t;
    int i;
    while (*p != '\0')
    {
        len++;
        p++;
    }

    if (m <= len)
    {
        for (i = 0; t[m - 1 + i] != '\0'; i++)
        {
            s[i] = t[m - 1 + i];
        }
        s[i] = '\0';
    }
    else
    {
        *s = '\0';
    }
}