C++典型案例分析

C++簡樸程序經(jīng)典案例【案例2-1】設計一種編寫僅包括C++程序基本構成元素的程序/*

//注釋行開始ThisisthefirstC++program.

Designedbyzrf*/

//注釋行結束#include<iostream>

//包括頭文獻usingnamespacestd;

//打開命名空間std//Thisisthemainfunction

//單行注釋語句intmain(void)

//主函數(shù)，程序入口{

//塊作用域開始intage;

//申明一種變量age=20;

//賦值語句cout<<"Theageis:\n";

//輸出一種字符串cout<<age<<endl;

//輸出變量中的值return0;

//主函數(shù)返回0}

//塊作用域結束

【案例2-2】計算圓的周長和面積——C++語言中常量、變量#include<iostream>usingnamespacestd;intmain(){

constfloatPI=3.1415926;

//float型常量floatr=2.0;

//用float型常量初始化變量cout<<"r="<<r<<endl;

//輸出圓的半徑floatlength;

//float型變量申明length=2*PI*r;

//計算圓的周長cout<<"Length="<<length<<endl;

//輸出圓的周長floatarea=PI*r*r;

//計算圓的面積cout<<"Area="<<area<<endl;

//輸出圓的面積return0;}【案例2-3】整數(shù)的簡樸運算——除法、求余運算法和增量減量運算符#include<iostream>usingnamespacestd;intmain(){

intx,y;x=10;

y=3;cout<<x<<"/"<<y<<"is"<<x/y

//整數(shù)的除法操作<<"withx%yis"<<x%y<<endl;

//整數(shù)的取余操作x++;

--y;

//使用增量減量運算符cout<<x<<"/"<<y<<"is"<<x/y<<"\n"

//整數(shù)的除法操作<<x<<"%"<<y<<"is"<<x%y<<endl;

//整數(shù)的取余操作return0;}【案例2-4】多重計數(shù)器——前置和后置自增運算符#include<iostream>

usingnamespacestd;

intmain()

{

intiCount=1;

iCount=(iCount++)+(iCount++)+(iCount++);

//后置++cout<<"Thefirst

iCount="<<iCount<<endl;iCount=1;

iCount=(++iCount)+(++iCount)+(++iCount);

//前置++cout<<"ThesecondiCount="<<iCount<<endl;iCount=1;

iCount=-iCount++;

//后置++cout<<"Thethird

iCount="<<iCount<<endl;iCount=1;

iCount=-++iCount;

//前置++cout<<"Thefourth

iCount="<<iCount<<endl;return0;

}【案例2-5】對整數(shù)“10”和“20”進行位運算——位運算的應用#include<iostream>usingnamespacestd;intmain()

{

cout<<"20&10="<<(20&10)<<endl;

//按位與運算cout<<"20^10="<<(20^10)<<endl;

//按位異或運算cout<<"20|10="<<(20|10)<<endl;

//按位或運算cout<<"~20="<<(~20)<<endl;

//按位取反運算cout<<"20<<3="<<(20<<3)<<endl;

//左移位運算cout<<"-20<<3="<<(-20<<3)<<endl;

//左移位運算cout<<"20>>3="<<(20>>3)<<endl;

//右移位運算cout<<"-20>>3="<<(-20>>3)<<endl;

//右移位運算return0;}【案例2-6】實現(xiàn)邏輯“異或”運算——邏輯運算應用#include<iostream>usingnamespacestd;intmain(){

boolp,q;p=true;

q=true;cout<<p<<"XOR"<<q<<"is"<<((p||q)&&!(p&&q))<<"\n";//輸出異或成果p=false;

q=true;cout<<p<<"XOR"<<q<<"is"<<((p||q)&&!(p&&q))<<"\n";//輸出異或成果p=true;

q=false;cout<<p<<"XOR"<<q<<"is"<<((p||q)&&!(p&&q))<<"\n";//輸出異或成果p=false;

q=false;cout<<p<<"XOR"<<q<<"is"<<((p||q)&&!(p&&q))<<"\n";//輸出異或成果return0;}【案例2-7】高效篩選器——用條件運算符“?”構建條件體現(xiàn)式#include<iostream>usingnamespacestd;intmain()

{

intiNum1=1,iNum2,iMax;cout<<"Pleaseinputtwointegers:\n";

cin>>iNum1>>iNum2;iMax=iNum1>iNum2?iNum1:iNum2;

//使用條件運算符構建條件體現(xiàn)式cout<<"Themaxintegeris:"<<iMax<<endl;return0;}【案例2-8】“多計算與單提取”功能的實現(xiàn)——逗號體現(xiàn)式#include<iostream>usingnamespacestd;intmain()

{

intVal1,Val2,Val3,Left,Midd,Righ;Left=10;

Midd=20;

Righ=30;Val1=(Left++,--Midd,Righ++);

//使用逗號體現(xiàn)式Val2=(Righ++,Left++,--Midd);

//使用逗號體現(xiàn)式Val3=(--Midd,Righ++,Left++);

//使用逗號體現(xiàn)式cout<<"Val1=\t"<<Val1<<"\nVal2=\t"<<Val2<<"\nVal3=\t"<<Val3<<endl;return0;}【案例2-9】高效的算術運算符——復合賦值運算符#include<iostream>usingnamespacestd;intmain(){

intn=20;

cout<<"n="<<n<<endl;n+=8;

cout<<"Aftern+=8,n="<<n<<endl;

//使用復合的賦值運算符+=n-=6;

cout<<"Aftern-=6,n="<<n<<endl;

//使用復合的賦值運算符-=n*=1;

cout<<"Aftern*=1,n="<<n<<endl;

//使用復合的賦值運算符*=n/=4;

cout<<"Aftern/=4,n="<<n<<endl;

//使用復合的賦值運算符/=n%=3;

cout<<"Aftern%=3,n="<<n<<endl;

//使用復合的賦值運算符%=return0;}【案例2-10】計算不一樣數(shù)據(jù)類型的存儲容量——sizeof運算符#include<iostream>usingnamespacestd;intmain(){

cout<<"Thesizeofanintis:\t\t"<<sizeof(int)<<"bytes.\n";cout<<"Thesizeofashortintis:\t"<<sizeof(short)<<"bytes.\n";cout<<"Thesizeofalongintis:\t"<<sizeof(long)<<"bytes.\n";cout<<"Thesizeofacharis:\t\t"<<sizeof(char)<<"bytes.\n";cout<<"Thesizeofawchar_tis:\t"<<sizeof(wchar_t)<<"bytes.\n";cout<<"Thesizeofafloatis:\t\t"<<sizeof(float)<<"bytes.\n";cout<<"Thesizeofadoubleis:\t"<<sizeof(double)<<"bytes.\n";return0;}【案例2-11】巧妙獲取整數(shù)部分——double和int數(shù)據(jù)類型的轉換#include<iostream>usingnamespacestd;intmain(){

intnn=10,mm;doublexx=4.741,yy;cout<<"nn*xx="<<nn*xx<<endl;

//體現(xiàn)式類型轉換mm=xx;

yy=nn;

//賦值類型轉換cout<<"mm="<<mm<<endl<<"yy="<<yy<<endl;cout<<"int(xx)="<<int(xx)<<endl<<"(int)xx="<<(int)xx<<endl;

//強制類型轉換cout<<"int(1.412+xx)="<<int(1.412+xx)<<endl;

//強制類型轉換cout<<"(int)1.412+xx="<<(int)1.412+xx<<endl;

//強制類型轉換return0;}【案例2-12】將分數(shù)轉換為小數(shù)——強制類型轉換#include<iostream>usingnamespacestd;intmain(){

for(inti=1;i<=5;++i)cout<<i<<"/3is:"<<(float)i/3<<endl;

//強制類型轉換return0;}【案例2-13】安全的除法計算器#include<iostream>usingnamespacestd;intmain(){

inta,b;cout<<"Enternumerator:";

cin>>a;cout<<"Enterdenominator:";

cin>>b;if(b)cout<<"DivideResultis:"<<a/b<<'\n';

//排除除數(shù)為零的狀況elsecout<<"Dividebyzero!\n";return0;}【案例2-14】猜數(shù)游戲——嵌套的if條件語句#include<iostream>#include<cstdlib>usingnamespacestd;intmain(){

intMagNum,GueNum;

MagNum=rand();

//產(chǎn)生隨機數(shù)cout<<"EntertheGuessnumber:";

cin>>GueNum;if(GueNum==MagNum){

//if語句塊起始位置cout<<"*ItisRight*\n"<<MagNum<<"istheMagessnumber.\n";}

//if語句塊結束位置else{

//else語句塊起始位置cout<<"Sorry,you'rewrong."<<endl;if(GueNum>MagNum)

cout<<"Guessednumberistoohigh.\n";else

cout<<"Guessednumberistoolow.\n";}

//else語句塊結束位置return0;}【案例2-15】根據(jù)輸入月份輸出從年初到本月底的天數(shù)——不帶break的switch#include<iostream>usingnamespacestd;intmain(){

intyear,month,days=0;cout<<"Inputyearandmonth:";

cin>>year>>month;switch(month)

//每個case分支均沒有break語句{

case12:days+=31;case11:days+=30;case10:days+=31;case

9:days+=30;case

8:days+=31;case

7:days+=31;case

6:days+=30;case

5:days+=31;case

4:days+=30;case

3:days+=31;case

2:

//判斷與否為閏年if(year%4==0&&year%100!=0||year%400==0)

days+=29;else

days+=28;case

1:days+=31;}if(days==0)

cout<<"Wrongmonth"<<endl;else

cout<<"Totaldaysis:"<<days<<endl;return0;}【案例2-16】計算數(shù)的階乘——do-while循環(huán)語句#include<iostream>usingnamespacestd;intmain(){

longlimits;cout<<"Enterapositiveinteger:";

cin>>limits;cout<<"Factorialnumbersof"<<0<<"is"<<1<<endl;cout<<"Factorialnumbersof"<<1<<"is"<<1<<endl;longfac=1,i=1;do

//使用do-while循環(huán){

fac*=++i;

cout<<"Factorialnumbersof"<<i<<"is"<<fac<<endl;}while(fac<limits);return0;}【案例2-17】計算數(shù)的階乘——for循環(huán)#include<iostream>usingnamespacestd;intmain(){

longlimits;cout<<"Enterapositiveinteger:";

cin>>limits;cout<<"Factorialnumbersof"<<0<<"is"<<1<<endl;cout<<"Factorialnumbersof"<<1<<"is"<<1<<endl;longfac=1;for(inti=2;fac<=limits;i++)

//使用for循環(huán){

fac*=i;cout<<"Factorialnumbersof"<<i<<"is"<<fac<<endl;}return0;}【案例2-18】篩選素數(shù)——步長為2的for循環(huán)#include<iostream>#include<cstdlib>usingnamespacestd;intmain(){

longn;cout<<"Enterapositiveinteger:";

cin>>n;if(n<2)

cout<<n<<"isnotprime."<<endl;elseif(n<4)

cout<<n<<"isprime."<<endl;elseif(n%2==0)

cout<<n<<"=2*"<<n/2<<endl;else{

for(inti=3;i<=n/2;i+=2)

//步長為2if(n%i==0)

{cout<<n<<"="<<i<<"*"<<n/i<<endl;

exit(0);}cout<<n<<"isprime."<<endl;}return0;}【案例2-19】輸出1~20之間的偶數(shù)——continue語句#include<iostream>usingnamespacestd;intmain(){

cout<<"Theevennumbersareasfollows:"<<endl;for(inti=0;i<=20;i++){

if(i%2)continue;

//根據(jù)條件使用continue結束本次循環(huán)cout<<i<<'';}return0;}【案例2-20】記錄輸入整數(shù)的個數(shù)并求和——exit()函數(shù)#include<iostream>#include<cstdlib>usingnamespacestd;intmain(){

intsum=0,num=0,m;cout<<"Pleaseinputintegers(0:end):"<<endl;do{cin>>m;

num++;

sum+=m;if(m==0){cout<<"Enterednumbers:"<<num<<"integers.\n";cout<<"Thesumis:"<<sum<<endl;exit(0);

//使用exit()函數(shù)終止程序}}while(1);return0;}【案例2-21】“剪刀、石頭、布”游戲——枚舉類型#include<iostream>usingnamespacestd;enumChoice{ROCK,CLOTH,SCISS};

//申明枚舉類型ChoiceenumWinner{Play1,Play2,Tie};

//申明枚舉類型Winnerintmain(){

intn;

Choicecho1,cho2;

Winnerwinner;cout<<"Chooserock(0),cloth(1),orSciss(2):"<<endl;cout<<"PlayerNo.1:";

cin>>n;

cho1=Choice(n);cout<<"PlayerNo.2:";

cin>>n;

cho2=Choice(n);if(cho1==cho2)winner=Tie;elseif(cho1==ROCK)if(cho2==CLOTH)

winner=Play2;else

winner=Play1;elseif(cho1==CLOTH)if(cho2==SCISS)

winner=Play2;else

winner=Play1;elseif(cho2==ROCK)

winner=Play2;else

winner=Play1;if(winner==Tie)

cout<<"\tTied!\n";elseif(winner==Play1)

cout<<"\tPlayerNo.1wins."<<endl;else

cout<<"\tPlayerNo.2wins."<<endl;return0;}【案例2-22】簡樸的學生信息類型——構造體#include<iostream>#include<iomanip>usingnamespacestd;structstudent

//學生信息構造體{

intnum;charname[20];chargender;intage;}stu1={1001,"ZhangSan",'M',19};intmain(){

studentstu2={1002,"LiSi",'M',20};

//申明構造體變量并初始化studentstu3={1003,"WangHong",'F',22};