/* This function will return the length of a string, which terminate will null character. */
rt_size_t rt_strlen(const char *s)
/* This function will return the length of a string, which terminate will null character. */
rt_size_t rt_strlen(const char *s)
{
    const char *sc;
    for (sc = s; *sc != '\0'; ++sc)
        ;
    return sc - s;
}