输入输出格式.docx

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1、关于输入输出的格式由于课程作业的需要，我们对程序作业的输入输出的格式有一定的要求，每个输入的数据都放在input.txt文件中，输出的数据都存在output.txt文件中。求两个数的和：输入示例输出示例input.txtoutput.txt235下面是一个在标准C++中求和的输入输出的例子：实现的算法#includeusingnamespacestd;intmain(){inta,b;ifstreamfin("input.txt");ofstreamfout("output.txt");fin>

2、>a>>b;fout<intmain(){inta,b;freopen("input.txt","r",stdin);freopen("output.txt","w",stdout);scanf("%d%d",&a,&b);printf("%d",a+b);return0;}(关于freopen函数及stdin、stdout的说明见附录。)然而在线评测系统出于安全因素的考虑，禁止了程序对

3、文件IO方面的权限，在线测试系统中，我们只需将freopen("input.txt","r",stdin);freopen("output.txt","w",stdout);1这两句注释掉即可。说明附录：FILE*freopen(constchar*path,constchar*mode,FILE*stream);Reassignafilepointer.参数说明：pathPathofnewfilemodeTypeofaccesspermittedstreamPointertoFILEstructurefreop

4、enistypicallyusedtoredirectthepre-openedfilesstdin,stdout,andstderrtofilesspecifiedbytheuser.Thenewfileassociatedwithstreamisopenedwithmode,whichisacharacterstringspecifyingthetypeofaccessrequestedforthefile,asfollows:"r"Opensforreading.Ifthefiledoesnotexisto

5、rcannotbefound,thefreopencallfails."w"Opensanemptyfileforwriting.Ifthegivenfileexists,itscontentsaredestroyed."a"Opensforwritingattheendofthefile(appending)withoutremovingtheEOFmarkerbeforewritingnewdatatothefile;createsthefilefirstifitdoesnotexist."r+"Opensf

6、orbothreadingandwriting.(Thefilemustexist.)"w+"Opensanemptyfileforbothreadingandwriting.Ifthegivenfileexists,itscontentsaredestroyed.stdin,stdout,stderr2FILE*stdin;FILE*stdout;FILE*stderr;#includeRemarksThesearestandardstreamsforinput,output,anderror

7、output.Bydefault,standardinputisreadfromthekeyboard,whilestandardoutputandstandarderrorareprintedtothescreen.Thefollowingstreampointersareavailabletoaccessthestandardstreams:PointerStreamstdinStandardinputstdoutStandardoutputstderrStandarderrorThesepointersca

8、nbeusedasargumentstofunctions.Somefunctions,suchasgetcharandputchar,usestdinandstdoutautomatically.Thesepointersareconstants,andcannotbeassignednewvalues.Thefreopenfunctioncanbeusedtoredi