token.c

char *strtok(char *str, const char *delimiters)
{
    char *token = NULL;
    static char *begin = NULL;
    if(str != NULL)
    {
        begin = str;
    }
    else
    {
        if(begin == NULL)
            return NULL;
    }

    char *p = begin;  // scan begin location
    //printf("p %p -%c-\n", p, *p);
    while(*p)
    {
        if(strchr(delimiters, *p) != NULL)
        {
            *p = '\0';
            p++;
            break;
        }
        p++;
    }

    
    token = begin;
    if(*p == '\0')  // reach original string ending
    {
        begin = NULL;
    }
    else
    {
        begin = p;  // new begin
    }
    
    
    return token;
}