C++典型案例分析

C++简朴程序经典案例【案例2-1】设计一种编写仅包括C++程序基本构成元素的程序/*

//注释行开始ThisisthefirstC++program.

Designedbyzrf*/

//注释行结束#include<iostream>

//包括头文献usingnamespacestd;

//打开命名空间std//Thisisthemainfunction

//单行注释语句intmain(void)

//主函数，程序入口{

//块作用域开始intage;

//申明一种变量age=20;

//赋值语句cout<<"Theageis:\n";

//输出一种字符串cout<<age<<endl;

//输出变量中的值return0;

//主函数返回0}

//块作用域结束

【案例2-2】计算圆的周长和面积——C++语言中常量、变量#include<iostream>usingnamespacestd;intmain(){

constfloatPI=3.1415926;

//float型常量floatr=2.0;

//用float型常量初始化变量cout<<"r="<<r<<endl;

//输出圆的半径floatlength;

//float型变量申明length=2*PI*r;

//计算圆的周长cout<<"Length="<<length<<endl;

//输出圆的周长floatarea=PI*r*r;

//计算圆的面积cout<<"Area="<<area<<endl;

//输出圆的面积return0;}【案例2-3】整数的简朴运算——除法、求余运算法和增量减量运算符#include<iostream>usingnamespacestd;intmain(){

intx,y;x=10;

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

//整数的除法操作<<"withx%yis"<<x%y<<endl;

//整数的取余操作x++;

--y;

//使用增量减量运算符cout<<x<<"/"<<y<<"is"<<x/y<<"\n"

//整数的除法操作<<x<<"%"<<y<<"is"<<x%y<<endl;

//整数的取余操作return0;}【案例2-4】多重计数器——前置和后置自增运算符#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】对整数“10”和“20”进行位运算——位运算的应用#include<iostream>usingnamespacestd;intmain()

{

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

//按位与运算cout<<"20^10="<<(20^10)<<endl;

//按位异或运算cout<<"20|10="<<(20|10)<<endl;

//按位或运算cout<<"~20="<<(~20)<<endl;

//按位取反运算cout<<"20<<3="<<(20<<3)<<endl;

//左移位运算cout<<"-20<<3="<<(-20<<3)<<endl;

//左移位运算cout<<"20>>3="<<(20>>3)<<endl;

//右移位运算cout<<"-20>>3="<<(-20>>3)<<endl;

//右移位运算return0;}【案例2-6】实现逻辑“异或”运算——逻辑运算应用#include<iostream>usingnamespacestd;intmain(){

boolp,q;p=true;

q=true;cout<<p<<"XOR"<<q<<"is"<<((p||q)&&!(p&&q))<<"\n";//输出异或成果p=false;

q=true;cout<<p<<"XOR"<<q<<"is"<<((p||q)&&!(p&&q))<<"\n";//输出异或成果p=true;

q=false;cout<<p<<"XOR"<<q<<"is"<<((p||q)&&!(p&&q))<<"\n";//输出异或成果p=false;

q=false;cout<<p<<"XOR"<<q<<"is"<<((p||q)&&!(p&&q))<<"\n";//输出异或成果return0;}【案例2-7】高效筛选器——用条件运算符“?”构建条件体现式#include<iostream>usingnamespacestd;intmain()

{

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

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

//使用条件运算符构建条件体现式cout<<"Themaxintegeris:"<<iMax<<endl;return0;}【案例2-8】“多计算与单提取”功能的实现——逗号体现式#include<iostream>usingnamespacestd;intmain()

{

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

Midd=20;

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

//使用逗号体现式Val2=(Righ++,Left++,--Midd);

//使用逗号体现式Val3=(--Midd,Righ++,Left++);

//使用逗号体现式cout<<"Val1=\t"<<Val1<<"\nVal2=\t"<<Val2<<"\nVal3=\t"<<Val3<<endl;return0;}【案例2-9】高效的算术运算符——复合赋值运算符#include<iostream>usingnamespacestd;intmain(){

intn=20;

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

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

//使用复合的赋值运算符+=n-=6;

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

//使用复合的赋值运算符-=n*=1;

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

//使用复合的赋值运算符*=n/=4;

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

//使用复合的赋值运算符/=n%=3;

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

//使用复合的赋值运算符%=return0;}【案例2-10】计算不一样数据类型的存储容量——sizeof运算符#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】巧妙获取整数部分——double和int数据类型的转换#include<iostream>usingnamespacestd;intmain(){

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

//体现式类型转换mm=xx;

yy=nn;

//赋值类型转换cout<<"mm="<<mm<<endl<<"yy="<<yy<<endl;cout<<"int(xx)="<<int(xx)<<endl<<"(int)xx="<<(int)xx<<endl;

//强制类型转换cout<<"int(1.412+xx)="<<int(1.412+xx)<<endl;

//强制类型转换cout<<"(int)1.412+xx="<<(int)1.412+xx<<endl;

//强制类型转换return0;}【案例2-12】将分数转换为小数——强制类型转换#include<iostream>usingnamespacestd;intmain(){

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

//强制类型转换return0;}【案例2-13】安全的除法计算器#include<iostream>usingnamespacestd;intmain(){

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

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

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

//排除除数为零的状况elsecout<<"Dividebyzero!\n";return0;}【案例2-14】猜数游戏——嵌套的if条件语句#include<iostream>#include<cstdlib>usingnamespacestd;intmain(){

intMagNum,GueNum;

MagNum=rand();

//产生随机数cout<<"EntertheGuessnumber:";

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

//if语句块起始位置cout<<"*ItisRight*\n"<<MagNum<<"istheMagessnumber.\n";}

//if语句块结束位置else{

//else语句块起始位置cout<<"Sorry,you'rewrong."<<endl;if(GueNum>MagNum)

cout<<"Guessednumberistoohigh.\n";else

cout<<"Guessednumberistoolow.\n";}

//else语句块结束位置return0;}【案例2-15】根据输入月份输出从年初到本月底的天数——不带break的switch#include<iostream>usingnamespacestd;intmain(){

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

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

//每个case分支均没有break语句{

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:

//判断与否为闰年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】计算数的阶乘——do-while循环语句#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循环{

fac*=++i;

cout<<"Factorialnumbersof"<<i<<"is"<<fac<<endl;}while(fac<limits);return0;}【案例2-17】计算数的阶乘——for循环#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循环{

fac*=i;cout<<"Factorialnumbersof"<<i<<"is"<<fac<<endl;}return0;}【案例2-18】筛选素数——步长为2的for循环#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)

//步长为2if(n%i==0)

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

exit(0);}cout<<n<<"isprime."<<endl;}return0;}【案例2-19】输出1~20之间的偶数——continue语句#include<iostream>usingnamespacestd;intmain(){

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

if(i%2)continue;

//根据条件使用continue结束本次循环cout<<i<<'';}return0;}【案例2-20】记录输入整数的个数并求和——exit()函数#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()函数终止程序}}while(1);return0;}【案例2-21】“剪刀、石头、布”游戏——枚举类型#include<iostream>usingnamespacestd;enumChoice{ROCK,CLOTH,SCISS};

//申明枚举类型ChoiceenumWinner{Play1,Play2,Tie};

//申明枚举类型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】简朴的学生信息类型——构造体#include<iostream>#include<iomanip>usingnamespacestd;structstudent

//学生信息构造体{

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

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

//申明构造体变量并初始化studentstu3={1003,"WangHong",'F',22};