scanf()输入问题

显示全部楼层 · 2021-1-27 06:52:08

#include
intmain()
{
inta,b;
floatx,y;
charc1,c2;
scanf("a=%db=%d",&a,&b);
scanf("%f%e",&x,&y);
scanf("%c%c",&c1,&c2);
printf("a=%db=%dx=%fy=%fc1=%cc2=%c",a,b,x,y,c1,c2);
return0;
}

我输入c1=A，c2=a而输出却是c1=c2=A???????
分 -->

千问 · 2021-1-27 06:52:08

不知道楼主在说什么的飘过。

千问 · 2021-1-27 06:52:08

应该是读到缓冲区中的回车符，就是之前输入数字的时候输入的回车符
你在第一个%c前面加一个空格可能就可以了
scanf("%c%c",&c1,&c2);

千问 · 2021-1-27 06:52:08

把完整的输入写出来。
不过估计就是2楼说的原因。

千问 · 2021-1-27 06:52:08

scanf();是格式化输入，你从控制台输入格式要一样，输入的空格逗号要和scanf中的一样
scanf("%c%c",&c1,&c2);这样的话输入2个字母中间就不能有别的，空格逗号都不行

千问 · 2021-1-27 06:52:08

#include
intmain()
{
inta,b;
floatx,y;
charc1,c2;
scanf("%d%d",&a,&b);//a=什么的去掉
scanf("%f%e",&x,&y);
scanf("%s%s",&c1,&c2);//把%c改成%s
printf("a=%db=%dx=%fy=%fc1=%cc2=%c",a,b,x,y,c1,c2);
return0;
}

千问 · 2021-1-27 06:52:08

使用scanf需要先清除缓冲区，还有两个输入数之间最好用逗号隔开，故将程序改成如下：
#include
intmain()
{
inta,b;
floatx,y;
charc1,c2;
fflush(stdin);
scanf("%d,%d",&a,&b);
fflush(stdin);
scanf("%f,%e",&x,&y);
fflush(stdin);
scanf("%c%c",&c1,&c2);
fflush(stdin);
printf("a=%db=%dx=%fy=%fc1=%cc2=%c",a,b,x,y,c1,c2);
scanf("%d",&a);//暂停用，这样会看到结果，不会一闪而过
return0;
}

千问 · 2021-1-27 06:52:08

FormatSpecificationFields:scanfandwscanfFunctions
Aformatspecificationhasthefollowingform:
%

[width][{h|l|I64|L}]type
Theformatargumentspecifiestheinterpretationoftheinputandcancontainoneormoreofthefollowing:
White-spacecharacters:blank('');tab('\t');ornewline('\n').Awhite-spacecharactercausesscanftoread,butnotstore,allconsecutivewhite-spacecharactersintheinputuptothenextnon–white-spacecharacter.Onewhite-spacecharacterintheformatmatchesanynumber(including0)andcombinationofwhite-spacecharactersintheinput.

Non–white-spacecharacters,exceptforthepercentsign(%).Anon–white-spacecharactercausesscanftoread,butnotstore,amatchingnon–white-spacecharacter.Ifthenextcharacterinstdindoesnotmatch,scanfterminates.

Formatspecifications,introducedbythepercentsign(%).Aformatspecificationcausesscanftoreadandconvertcharactersintheinputintovaluesofaspecifiedtype.Thevalueisassignedtoanargumentintheargumentlist.
Theformatisreadfromlefttoright.Charactersoutsideformatspecificationsareexpectedtomatchthesequenceofcharactersinstdin;thematchingcharactersinstdinarescannedbutnotstored.Ifacharacterinstdinconflictswiththeformatspecification,scanfterminates,andthecharacterisleftinstdinasifithadnotbeenread.
Whenthefirstformatspecificationisencountered,thevalueofthefirstinputfieldisconvertedaccordingtothisspecificationandstoredinthelocationthatisspecifiedbythefirstargument.Thesecondformatspecificationcausesthesecondinputfieldtobeconvertedandstoredinthesecondargument,andsoonthroughtheendoftheformatstring.
Aninputfieldisdefinedasallcharactersuptothefirstwhite-spacecharacter(space,tab,ornewline),oruptothefirstcharacterthatcannotbeconvertedaccordingtotheformatspecification,oruntilthefieldwidth(ifspecified)isreached.Iftherearetoomanyargumentsforthegivenspecifications,theextraargumentsareevaluatedbutignored.Theresultsareunpredictableiftherearenotenoughargumentsfortheformatspecification.
Eachfieldoftheformatspecificationisasinglecharacteroranumbersignifyingaparticularformatoption.Thetypecharacter,whichappearsafterthelastoptionalformatfield,determineswhethertheinputfieldisinterpretedasacharacter,astring,oranumber.
Thesimplestformatspecificationcontainsonlythepercentsignandatypecharacter(forexample,%s).Ifapercentsign(%)isfollowedbyacharacterthathasnomeaningasaformat-controlcharacter,thatcharacterandthefollowingcharacters(uptothenextpercentsign)aretreatedasanordinarysequenceofcharacters,thatis,asequenceofcharactersthatmustmatchtheinput.Forexample,tospecifythatapercent-signcharacteristobeinput,use%%.
Anasterisk(*)followingthepercentsignsuppressesassignmentofthenextinputfield,whichisinterpretedasafieldofthespecifiedtype.Thefieldisscannedbutnotstored.

千问 · 2021-1-27 06:52:08

你要弄清楚标准IO
（1）行缓冲
（2）无缓冲
（3）全缓冲
这三个的概念,有些问题本身其实没有价值,问题本身引发的东西也许更有价值。

千问 · 2021-1-27 06:52:08

你向两个%c中间加个空格试试