C小程序 - 处理传入参数的一种方法

usage: program [ -i ] src dest

main(int ac, char *av[])
{

    char    *src = NULL, *dest = NULL;
    int    i_option = 0;
                        /* check args     */
    while( --ac ){
        if ( strcmp("-i", *++av) == 0 )
            i_option = 1;
        else if ( !src )
            src = *av;
        else if ( !dest )
            dest = *av;
        else
            usage();
        }
    if ( !src || !dest )
        usage();
}