C++快速入门国外大神的教程Word文件下载.docx
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C++快速入门国外大神的教程Word文件下载.docx
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//Thisvalueservesastheprogram'
sexitstatus.
//Seehttp:
//en.wikipedia.org/wiki/Exit_statusformoreinformation.
intmain(intargc,char**argv)
{
//Commandlineargumentsarepassedinbyargcandargvinthesameway
//theyareinC.
//argcindicatesthenumberofarguments,
//andargvisanarrayofC-stylestrings(char*)
//representingthearguments.
//Thefirstargumentisthenamebywhichtheprogramwascalled.
//argcandargvcanbeomittedifyoudonotcareaboutarguments,
//givingthefunctionsignatureofintmain()
//Anexitstatusof0indicatessuccess.
return0;
}
//However,C++variesinsomeofthefollowingways:
//InC++,characterliteralsarechars
sizeof('
c'
)==sizeof(char)==1
//InC,characterliteralsareints
)==sizeof(int)
//C++hasstrictprototyping
voidfunc();
//functionwhichacceptsnoarguments
//InC
//functionwhichmayacceptanynumberofarguments
//UsenullptrinsteadofNULLinC++
int*ip=nullptr;
//CstandardheadersareavailableinC++,
//butareprefixedwith"
c"
andhaveno.hsuffix.
#include<
cstdio>
intmain()
printf("
Hello,world!
\n"
);
///////////////////////
//Functionoverloading
//C++supportsfunctionoverloading
//providedeachfunctiontakesdifferentparameters.
voidprint(charconst*myString)
String%s\n"
myString);
voidprint(intmyInt)
Myintis%d"
myInt);
print("
Hello"
//Resolvestovoidprint(constchar*)
print(15);
//Resolvestovoidprint(int)
/////////////////////////////
//Defaultfunctionarguments
//Youcanprovidedefaultargumentsforafunction
//iftheyarenotprovidedbythecaller.
voiddoSomethingWithInts(inta=1,intb=4)
//Dosomethingwiththeintshere
doSomethingWithInts();
//a=1,b=4
doSomethingWithInts(20);
//a=20,b=4
doSomethingWithInts(20,5);
//a=20,b=5
//Defaultargumentsmustbeattheendoftheargumentslist.
voidinvalidDeclaration(inta=1,intb)//Error!
/////////////
//Namespaces
//Namespacesprovideseparatescopesforvariable,function,
//andotherdeclarations.
//Namespacescanbenested.
namespaceFirst{
namespaceNested{
voidfoo()
{
ThisisFirst:
:
Nested:
foo\n"
}
}//endnamespaceNested
}//endnamespaceFirst
namespaceSecond{
ThisisSecond:
voidfoo()
Thisisglobalfoo\n"
//IncludesallsymbolsfromnamespaceSecondintothecurrentscope.Note
//thatsimplyfoo()nolongerworks,sinceitisnowambiguouswhether
//we'
recallingthefooinnamespaceSecondorthetoplevel.
usingnamespaceSecond;
Second:
foo();
//prints"
foo"
First:
:
Thisisglobalfoo"
///////////////
//Input/Output
//C++inputandoutputusesstreams
//cin,cout,andcerrrepresentstdin,stdout,andstderr.
//<
<
istheinsertionoperatorand>
>
istheextractionoperator.
iostream>
//IncludeforI/Ostreams
usingnamespacestd;
//Streamsareinthestdnamespace(standardlibrary)
intmyInt;
//Printstostdout(orterminal/screen)
cout<
"
Enteryourfavoritenumber:
;
//Takesininput
cin>
myInt;
//coutcanalsobeformatted
Yourfavoritenumberis"
<
myInt<
Yourfavoritenumberis<
myInt>
"
cerr<
Usedforerrormessages"
//////////
//Strings
//StringsinC++areobjectsandhavemanymemberfunctions
string>
//Stringsarealsointhenamespacestd(standardlibrary)
stringmyString="
stringmyOtherString="
World"
//+isusedforconcatenation.
cout<
myString+myOthe
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