白小姐四肖必选一肖

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嵌入式C语言的小技巧帮您减少代码量

为了写出适应性更广的C语言白小姐四肖必选一肖程序,程序员考虑问题时应面面俱到。例如,在C语言程序中调用 open() 函数尝试打开文件时,应考虑到文件是否存在,当前程序是否有足够权限等情况。在打开文件失败时,需要做相应的错误处理,这样才能让程序的稳定性更强。

KANDAOZHEILI,XIANGXINYOUDUZHEYIJINGCHAJUEDAOLE,CUOWUCHULIYUJUHUIRANGZHENGGEDAIMAFANSUOXUDUO。LIRU:int fd = open("filename", O_RDWR);if(fd < 0){printf("open file failed, %mn");return -1;}if(sizeof("hello") != write(fd, "hello", sizeof("hello")) ){printf("write file failed, %mn"); close(fd);return -1;}close(fd);

SHANGMIANZHEIDUANCYUYANDAIMAZUOLEXIANGYINGDECUOWUCHULI,NENGGOUCHULIDAKAIWENJIANSHIBAI,HEXIESHUJUSHIBAIDEQINGKUANG。DANSHIDUOSHUQINGKUANGXIA,WOMENDECYUYANCHENGXUDOUBUTAIKENENGQUCAOZUOYIGEBUYUNXUCAOZUO,HUOZHEBUCUNZAICAOZUODEWENJIAN,ERXIESHUJUYEHENSHAOCHUXIANSHIBAIDEQINGKUANG。SHISHISHANG,RUGUOBUKAOLVJISHAOCHUXIANDEYIWAI,SHANGSHUCYUYANDAIMAKEYIZHEIMEXIE:int fd = open("filename", O_RDWR);write(fd, "hello", sizeof("hello"));close(fd);

XIANRAN,DAIMAJIANJIEDUOLE。KESHI,SUIRAN“YIWAI”CHUXIANDEJILVBIJIAODI,WOMENRENGRANBUNENGHULVETA,FOUZEYIDAN“YIWAI”CHUXIAN,CHENGXUBENGKUITUICHUHAIHAO,WANYICHENGXUJIXUYUNXING,ZAOCHENGBUKEYUZHIDECUOWUJIUMAFANLE。SUOYI,ZAIBIANXIECYUYANCHENGXUSHI,TIANJIAXIANGYINGDECUOWUPANDUANHECHULIYUJUSHIBIYAODE。

白小姐四肖必选一肖ZAICYUYANCHENGXUKAIFAZHONG,MOUGEHANSHUDEZHIXINGZHUANGTAICHANGCHANGSHIYONGFANHUIMAQUFEN,YEJI return DEZHI。JIUJINGHANSHUYINGGAIYONGSHENMEYANGDEFANHUIZHI,JUEDINGSHENMEZHIXINGZHUANGTAI,BINGMEIYOUQIANGZHIBIAOZHUN。BUGUO,DUIYU int FANHUIZHILEIXINGDEHANSHU,DADUOSHUCYUYANCHENGXUYUANDOUAISHIYONG return 0; BIAOSHIHANSHUZHIXINGCHENGGONG,HANSHUZHIXINGSHIBAISHI,ZEFANHUIYIGEFUZHI(RU return -1;)。

白小姐四肖必选一肖QINGKANXIAMIANZHEIGEHANSHU:int test(int val){if(val % 99999 == 0)return -1;printf("val = %dn", val);return0;}CONGSHANGSHUCYUYANDAIMAKEYIKANCHU,test() HANSHUJIESHOUYIGE int XINGDECANSHU val,RUGUO val WEI 99999 DEBEISHU,ZEFANHUI -1(ZHEILIRENWEICHUCUO),FOUZEDAYINCHU val DEZHIBINGFANHUI 0。

白小姐四肖必选一肖ANZHAOSHANGMIANDETAOLUN,KAIFACYUYANCHENGXUSHIYINGKAOLVGEZHONG“YIWAI”,ZAIDIAOYONG test() HANSHUSHI,XUYAOXIANGYINGDECUOWUCHULIDAIMA:if(-1 == test(val)){// do somethingreturn -1;}

ZAISHIJIDECYUYANXIANGMUKAIFAZHONG,YOUSHIHUIYUDAOZHONGFUDIAOYONGMOUGEHANSHUDEQINGKUANG,LIRU:if(-1 == test(a)){// do somethingreturn -1;}if(-1 == test(b)){// do somethingreturn -1;}if(-1 == test(c)){// do somethingreturn -1;}...if(-1 == test(m)){// do somethingreturn -1;}

test() HANSHUCHUCUODEJILVHENXIAO,DANSHIWEILECHENGXUDEWENDINGXING,RENGRANXUYAOXIANGYINGDECUOWUCHULIDAIMA。DANSHICUOWUCHULIYERANGBENLAIHENJIANJIEDEDAIMADUANBIANDE“LUOSUO”,ERQIEZHEIXIECUOWUCHULIDAIMABEIZHIXINGDEKENENGXINGWEIHUQIWEI。ZHEILIDEtest() HANSHUZHISHIWEILETAOLUNZHUTITICHUDELIZI。DUZHEYINGKAOLVSHIJIQINGKUANG,LIRU:MEIYOUCHENGXUYUANHUIDIAOYONG open() DAKAIYIGEBUYUNXUCAOZUODEWENJIAN,DANSHICUOWUCHULIDAIMARENGRANSHIBUKESHAODE。

DANGRAN,ZHONGFUDEDAIMAKEYISHIYONGHONGDINGYIFENGZHUANG,ZHEIYIDIANZHIQIANDEWENZHANGYIJINGTAOLUNGUO,BUZAIZHUISHULE。ZHIDESHUOMINGDELINGWAIYIGEBANFAJIUSHILIYONG test() ZHIXINGCHENGGONGSHIFANHUIZHIWEI 0 DETEDIAN,QINGKANXIAMIANZHEIDUANCYUYANDAIMA:int ret = 0;ret += test(a);ret += test(b);ret += test(c);...ret += test(m);if(0!=ret){// do somethingreturn -1;}

KEYIKANCHU,ZHEIYANGJIUZHIXUXIEYICHUCUOWUCHULIDAIMALE,ERQIEZHIYAOYOUYIGE test() ZHIXINGSHIBAI,CYUYANCHENGXUJIUHUIZHIXINGTA。ZHEIYANGSHIYIGEZHEZHONG,ZAIJINLIWEICHIDAIMAJIANJIEXINGDEJICHUSHANG,BAOLIUCUOWUCHULILUOJI。XIANRAN,ZHIYOU test() DECUOWUWUXULIKECHULISHICAINENGZHEIMEXIE。

白小姐四肖必选一肖YIBANLAISHUO,SHIYONG ret+=test ZHEZHONGFANGANZHISHIHEWUXULIKECHULICUOWUDEQINGKUANG,CISHISUOYOUDE test() DIAOYONGDOUBEISHIWEIDENGJIADECAOZUO。SUOYIZAICUOWUCHULIDAIMAZHONG,CHANGCHANGBUZAIKAOLVJIUJINGSHINAYIGE test() CHUCUO。BUGUO,RUGUOXIWANGZHIDAOJIUJINGSHINAGEHUOZHENAJIGEHANSHU test() CHUCUO,YESHIYOUBANFADE。

XIANRAN,YINGGAICONG test() HANSHUBENSHENRUSHOU。ZUIJIANDANDEBANFAJIUSHIZAI test() HANSHUFANHUI -1 ZHIQIANDAYINCHUSHURUDECANSHU,XIUGAIHOUDE test() DECYUYANDAIMARUXIA:int test(int val){if(val % 99999 == 0){printf("unexpected val: %dn", val);return -1;}printf("val = %dn", val);return0;}

ZHEIYANGJIUKEYITONGGUOSHURUDECANSHU val QUEDINGNAYIGE test() CHUCUOLE。BUGUOZHEIZHONGFANGFAYAOQIUGEGE test() JIESHOUDAODECANSHUGEBUXIANGTONG,FOUZEJIUSHIXIAOLE。