C++经典代码大全.doc

//根据半径计算圆的周长和面积
#include <iostream.h>
const float PI=3.1416; //声明常量(只读变量)PI为3.1416
float fCir_L(float); //声明自定义函数fCir_L()的原型
float fCir_S(float); //声明自定义函数fCir_S()的原型

//以下是main()函数
main()
{
float r,l,s; //声明3个变量

cout<<"R="; //显示字符串
cin>>r; //键盘输入
l=fCir_L(r); //计算圆的周长，赋值给变量l
s=fCir_S(r); //计算圆的面积，赋值给变量s
cout<<"l="<<l; //显示计算结果
cout<<"\ns="<<s;
}

//定义计算圆的周长的函数fCir_L()
float fCir_L(float x)
{
float z=-1.0; //声明局部变量
if (x>=0.0) //如果参数大于0，则计算圆的周长
z=2*PI*x;
return(z); //返回函数值
}

//定义计算圆的面积的函数fCir_S()
float fCir_S(float x)
{
float z=-1.0; //声明局部变量
if (x>=0.0) //如果参数大于0，则计算圆的面积
z=PI*x*x;
return(z); //返回函数值
}
/* Program: P1-2.CPP
Written by: Hap
Date written: 02:11:10
*/
#include <iostream.h>
void main(void)
{
double s1,s2,s3;
s1=1.5; /* 对变量s1赋值*/
cout<<"s1="<<s1<<endl;
/* 对变量s2赋值*/ s2=2.5;
cout<<"s2="<<s2<<endl;
s3= /* 对变量s3赋值*/ 3.5;
cout<<"s3="<<s3<<endl;

cout<<"s1+s2+s3="<<s1+s2+s3<<endl; //计算并显示
//计算并显示 cout<<"s1+s2+s3="<<s1+s2+s3<<endl;
}
#include <iostream.h>
main()
{
double r=1.0;
cout<<"r="<<r<<endl;
double l;
l=2*3.1416*r; //计算圆的周长，赋值给变量l
cout<<"l="<<l<<endl; //显示圆的周长
double s=3.1416*r*r; //计算圆的面积，赋值给变量s
cout<<"s="<<s<<endl; //显示圆的面积

cout<<"R="; //显示提示输入的信息
cin>>r; //键盘输入
l=2*3.1416*r; //计算圆的周长，赋值给变量l
cout<<"l="<<l<<endl; //显示圆的周长
s=3.1416*r*r;
cout<<"s="<<s<<endl; //显示圆的面积
}
#include <iostream.h> //包含iostream.h头文件
void main()
{
//输出字符常量、变量和字符串
char c1='A';
cout<<'W';
cout<<c1<<endl;
cout<<"This is a test."<<endl;
cout<<"------------------"<<endl;

//输出整型常量、变量和表达式
int n=100;
cout<<10;
cout<<n;
cout<<2*n<<endl; //输出整型表达式
cout<<"------------------"<<endl;

//输出浮点型常量、变量和表达式
double pi=3.1415926,r=10.0,s=pi*r*r;
cout<<pi<<endl;
cout<<r;
cout<<s;
cout<<2*r*pi<<endl; //输出浮点型表达式
cout<<"------------------"<<endl;

//一个cout可以输出多项数据
cout<<'W'<<" "<<c1<<endl;
cout<<"This is a test."<<endl;
cout<<"pi="<<pi<<" r="<<r<<" s="<<s<<endl;
}
#include <iostream.h> //包含iostream.h头文件
main()
{
//输入输出字符
char c;
cin>>c;
cout<<"c="<<c<<endl;

//输入输出整型数据
int n;
cin>>n;
cout<<"n="<<n<<endl;

//输入输出浮点型数据
double x;
cin>>x;
cout<<"x="<<x<<endl;

//输入提示
cout<<"n=";
cin>>n;
cout<<"n="<<n<<endl;

//多项输入
cout<<"c n x"<<endl;
cin>>c>>n>>x;
cout<<"c="<<c<<" n="<<n<<" x="<<x<<endl;
}
#include <iostream.h> //包含iostream.h头文件
main()
{
//声明整型变量
int a,b;

//从键盘上为整型变量赋值
cout<<"a=";
cin>>a;
cout<<"b=";
cin>>b;

//整型数的算术运算
cout<<a<<"+"<<b<<"="<<a+b<<endl;
cout<<a<<"-"<<b<<"="<<a-b<<endl;
cout<<a<<"*"<<b<<"="<<a*b<<endl;
cout<<a<<"/"<<b<<"="<<a/b<<endl;
cout<<a<<"%"<<b<<"="<<a%b<<endl;

//测试溢出
short n=32767,m; //n取short类型的最大值
cout<<"n="<<n<<endl;
m=n+1; //引起溢出
cout<<"n+1="<<m<<endl;
}
#include <iostream.h> //包含iostream.h头文件
main()
{
//声明变量，并初始化
int a=010,b=10,c=0X10;

//以十进制形式显示数据
cout<<"DEC:";
cout<<" a="<<a;
cout<<" b="<<b;
cout<<" c="<<c<<endl;

//以八进制形式显示数据
cout<<"OCT:";
cout<<oct; //指定八进制输出
cout<<" a="<<a;
cout<<" b="<<b;
cout<<" c="<<c<<endl;

//以十六进制形式显示数据
cout<<"HEX:";
cout<<hex; //指定十六进制输出
cout<<" a="<<a;
cout<<" b="<<b;
cout<<" c="<<c<<endl;

//八、十和十六进制数混合运算并输出
cout<<"a+b+c=";
cout<<dec; //恢复十进制输出
cout<<a+b+c<<endl;

//测试八、十和十六进制输入
cout<<"DEC:a="; cin>>a;
cout<<"OCT:b="; cin>>b;
cout<<"HEX:a="; cin>>c;
cout<<"DEC:"<<dec<<endl; //指定十进制输出
cout<<"a="<<a<<endl;
cout<<"b="<<b<<endl;
cout<<"c="<<c<<endl;
}
#include <iostream.h> //包含iostream.h头文件
#include<iomanip.h> // iomanip.h头文件包含setprecision()的定义
main()
{
//float型变量的声明、输入、计算和输出
float fx,fy;
cout<<"fx=";
cin>>fx;
cout<<"fy=";
cin>>fy;
cout<<fx<<"+"<<fy<<"="<<fx+fy<<endl;
cout<<fx<<"-"<<fy<<"="<<fx-fy<<endl;
cout<<fx<<"*"<<fy<<"="<<fx*fy<<endl;
cout<<fx<<"/"<<fy<<"="<<fx/fy<<endl<<endl;
//cout<<fx<<"%"<<fy<<"="<<fx%fy<<endl; Error!

//double型变量的声明、输入、计算和输出
float dx,dy;
cout<<"dx=";
cin>>dx;
cout<<"dy=";
cin>>dy;
cout<<dx<<"+"<<dy<<"="<<dx+dy<<endl;
cout<<dx<<"-"<<dy<<"="<<dx-dy<<endl;
cout<<dx<<"*"<<dy<<"="<<dx*dy<<endl;
cout<<dx<<"/"<<dy<<"="<<dx/dy<<endl<<endl;
//cout<<fx<<"%"<<fy<<"="<<fx%fy<<endl; Error!

//测试float和double类型数据的有效位
fx=10.0;fy=6.0;
float fz=fx/fy;
dx=10.0;dy=6.0;
double dz=dx/dy;
cout<<"fz=";
cout<<setprecision(20)<<fx<<"/"<<fy<<"="<<fz<<endl;
cout<<"dz=";
cout<<setprecision(20)<<dx<<"/"<<dy<<"="<<dz<<endl<<endl;;

//float型溢出
float x=3.5e14;
cout<<"x="<<x<<endl;
cout<<"x*x="<<x*x<<endl;
cout<<"x*x*x="<<x*x*x<<endl;
}
#include <iostream.h> //包含iostream.h头文件
main()
{
//字符类型变量的声明
char c1='A';
char c2;

//字符数据的运算及输出
c2=c1+32;
cout<<"c1="<<c1<<endl;
cout<<"c2="<<c2<<endl;

//输出字符及ASCII码
cout<<c1<<" : "<<int(c1)<<endl;
cout<<c2<<" : "<<int(c2)<<endl;
cout<<'$'<<" : "<<int('$')<<endl;

//输入字符
cout<<"c1 c2"<<endl;
cin>>c1>>c2;
cout<<"c1="<<c1<<" c2="<<c2<<endl;
}
#include <iostream.h> //包含iostream.h头文件
main()
{
char c1='\a',TAB='\t';

//阵铃一声
cout<<c1<<endl;

//使用水平制表符
cout<<1<<TAB<<2<<TAB<<3<<TAB<<4<<endl;

//使用双引号
cout<<"He said \"Thank you\"."<<endl;

//使用回车换行
cout<<"abc\n"<<"def"<<'\n';
}

#include <iostream.h> //包含iostream.h头文件
main()
{
//声明bool变量，并初始化
bool flag1=false,flag2=true;

//输出布尔常量和变量
cout<<"false:"<<false<<endl;
cout<<"true: "<<true<<endl;
cout<<"flag1="<<flag1<<endl;
cout<<"flag2="<<flag2<<endl;

//布尔变量的赋值和输出
int x=1;
flag1=x>0; //存放关系运算结果
cout<<"flag1="<<flag1<<endl;
flag2=flag1; //bool类型变量相互赋值
cout<<"flag2="<<flag2<<endl;

//布尔变量超界处理
flag1=100;
cout<<"flag1="<<flag1<<endl;
flag2=-100;
cout<<"flag2="<<flag2<<endl;
}
#include <iostream.h>
const double PI=3.1416; //声明常量(const变量)PI为3.1416
main()
{
//声明3个变量
double r,l,s;

//输入圆的半径
cout<<"r=";
cin>>r;

//计算圆的周长
l=2*PI*r;
cout<<"l="<<l<<endl;

//计算圆的面积
s=PI*r*r;
cout<<"s="<<s<<endl;
}

#include<iostream.h>
main()
{
//定义枚举类型，并指定其枚举元素的值
enum color {
RED=3,
YELLOW=6,
BLUE=9
};

//声明枚举变量a和b,并为枚举变量a赋初值
enum color a=RED;
color b; //合法，与C语言不同

// 输出枚举常量
cout<<"RED="<<RED<<endl;
cout<<"YELLOW="<<YELLOW<<endl;
cout<<"BLUE="<<BLUE<<endl;

//枚举变量的赋值和输出
b=a;
a=BLUE;
cout<<"a="<<a<<endl;
cout<<"b="<<b<<endl;
//a=100; 错误!
//a=6 也错误!

//枚举变量的关系运算
b=BLUE; // 枚举变量的赋值运算
cout<<"a<b="<<(a<b)<<endl;
}
#include <iostream.h>
const double PI=3.1416; //声明常量(const变量)PI为3.1416
main()
{
//声明3个变量
double r=3,l,s;

//计算圆的周长
l=2*PI*r;
cout<<"l="<<l<<endl;

//计算圆的面积
s=PI*r*r;
cout<<"s="<<s<<endl;

//验证赋值误差
int il,is;
il=l;
is=s;
cout<<"il="<<il<<endl;
cout<<"is="<<is<<endl;
}
#include <iostream.h>
main()
{
//变量声明
char c;
double x,y;

//测试自增
cout<<"++E and E++ :"<<endl;
c='B';
cout<<"c="<<++c<<endl; //输出c=C
c='B';
cout<<"c="<<c++<<endl; //输出c=B
x=1.5;
y=5+ ++x; //加号后的空格不能少
cout<<"y="<<y<<endl; //输出y=7.5
x=1.5;
y=5+x++;
cout<<"y="<<y<<endl; //输出y=6.5
cout<<"--------------------"<<endl;

//测试自减
cout<<"--E and E-- :"<<endl;
c='B';
cout<<"c="<<--c<<endl; //输出c=A
c='B';
cout<<"c="<<c--<<endl; //输出c=B
x=1.5;
y=5+--x;
cout<<"y="<<y<<endl; //输出y=5.5
x=1.5;
y=5+x--;
cout<<"y="<<y<<endl; //输出y=6.5
}
#include <iostream.h>
main()
{
int a=3, b=2;

//输出关系表达式
cout<<a<b<<endl;
cout<<(a<b)<<(a>b)<<(a>=b)<<(a==b)<<(a!=b)<<endl;

bool flag=2*a<b+10;
cout<<"flag="<<flag;
}
#include <iostream.h>
main()
{
float a=3.5,b=2.1,c=0;
cout<<"a="<<a<<" b="<<b<<" c="<<c<<endl;

//与运算
cout<<"a&&b="<<(a&&b)<<endl;//输出1
cout<<"a&&c="<<(a&&c)<<endl;//输出0

//或运算
cout<<"a||b="<<(a||b)<<endl;//输出1
cout<<"a||c="<<(a||c)<<endl;//输出1

//非运算
cout<<"!a="<<!a<<endl<<"!c="<<!c<<endl;//输出0 1

//关系运算和逻辑运算
bool flag=a>=0 && a<=5; //变量a在[0,5]区间内
cout<<"a=>0 && a<=5="<<flag<<endl;//输出1

//算术运算、关系运算和逻辑运算
cout<<"a+5>2*b+2||a<b+3="<<(a+5>2*b+2||a<b+3)<<endl;//输出1
}
#include <iostream.h>
main()
{
//按位与运算
cout<<"24&12="<<(24&12)<<endl;
//按位异或运算
cout<<"24^12="<<(24^12)<<endl;
//按位或运算
cout<<"24|12="<<(24|12)<<endl;
//按位取反运算
cout<<"~24="<<(~24)<<endl;

//左移位运算
cout<<"5<<3="<<(5<<3)<<endl;
cout<<"-5<<3="<<(-5<<3)<<endl;

//右移位运算
cout<<"5>>3="<<(5>>3)<<endl;
cout<<"-5>>3="<<(-5>>3)<<endl;
}
#include <iostream.h>
main()
{
int a=1,b=1,c=3;
//显示a,b,c的值
cout<<"a="<<a<<" b="<<b<<" c="<<c<<endl;

//计算显示(1) b+=a+2*c%5; 的结果
b+=a+2*c%5; //相当于表达式语句 b=b+(a+2*c%5);
cout<<"(1) b="<<b<<endl;

//计算显示(2) a<<=c-2*b; 的结果
a=1,b=1,c=3;
a<<=c-2*b; // 相当于表达式语句 a=a<<(c-2*b);
cout<<"(2) a="<<a<<endl;

//计算显示(3) a*=b=c=3;的结果
a=1,b=1,c=3;
a*=b=c=3; //相当于语句组 c=3;b=c;a=a*b;
cout<<"(3) a="<<a<<" b="<<b<<" c="<<c<<endl;

//计算显示(4) a+=b+=c;的结果
a=1,b=1,c=3;
a+=b+=c; //相当于语句组 b=b+c; a=a+b;
cout<<"(4) a="<<a<<" b="<<b<<" c="<<c<<endl;

//计算显示(5) a-=b=++c+2;的结果
a=1,b=1,c=3;
a-=b=++c+2; //相当于语句组 ++c;b=b+c+2;a=a-b;
cout<<"(5) a="<<a<<" b="<<b<<" c="<<c<<endl;
}
#include <iostream.h>
main()
{
//用 sizeof 计算各类种常量的字节长度
cout<<"sizeof('$')="<<sizeof('$')<<endl;
cout<<"sizeof(1)="<<sizeof(1)<<endl;
cout<<"sizeof(1.5)="<<sizeof(1.5)<<endl;
cout<<"sizeof(\"Good!\")="<<sizeof("Good!")<<endl;

//用sizeof 计算各类型变量的字节长度
int i=100;
char c='A';
float x=3.1416;
double p=0.1;
cout<<"sizeof(i)="<<sizeof(i)<<endl;
cout<<"sizeof(c)="<<sizeof(c)<<endl;
cout<<"sizeof(x)="<<sizeof(x)<<endl;
cout<<"sizeof(p)="<<sizeof(p)<<endl;

//用sizeof 计算表达式的字节长度
cout<<"sizeof(x+1.732)="<<sizeof(x+1.732)<<endl;

//用 sizeof 计算各类型的字节长度
cout<<"sizeof(char)="<<sizeof(char)<<endl;
cout<<"sizeof(int)="<<sizeof(int)<<endl;
cout<<"sizeof(float)="<<sizeof(float)<<endl;
cout<<"sizeof(double)="<<sizeof(double)<<endl;

//用sizeof 计算数组的字节长度
char str[]="This is a test.";
int a[10];
double xy[10];
cout<<"sizeof(str)="<<sizeof(str)<<endl;
cout<<"sizeof(a)="<<sizeof(a)<<endl;
cout<<"sizeof(xy)="<<sizeof(xy)<<endl;

//用sizeof 计算自定义类型的长度
struct st {
short num;
float math_grade;
float Chinese_grade;
float sum_grade;
};
st student1;
cout<<"sizeof(st)="<<sizeof(st)<<endl;
cout<<"sizeof(student1)="<<sizeof(student1)<<endl;
}
#include <iostream.h>
main()
{
//声明变量语句中使用顺序运算
int x, y;

//计算中使用顺序运算
x=50;
y=(x=x-5, x/5);
cout<<"x="<<x<<endl;
cout<<"y="<<y<<endl;
}
#include <iostream.h>
main()
{
//测试表达式类型的转换
int n=100,m;
double x=3.791,y;
cout<<"n*x="<<n*x<<endl;

//赋值类型转换
m=x;
y=n;
cout<<"m="<<m<<endl;
cout<<"y="<<y<<endl;

//强制类型转换
cout<<"int(x)="<<int(x)<<endl;
cout<<"(int)x="<<(int)x<<endl;
cout<<"int(1.732+x)="<<int(1.732+x)<<endl;
cout<<"(int)1.732+x="<<(int)1.723+x<<endl;
cout<<"double(100)="<<double(100)<<endl;
}
#include <iostream.h>
main()
{
float a,b,s;

cout<<"a b"<<endl;
cin>>a>>b; //利用cin从键盘上为变量 a,b 赋值
s=a;
if (a<b) {
s=b; //if语句中只有这一个语句，可省略花括号
}
s=s*s; //变量s中保存a,b中较大的一个数的平方
cout<<"s="<<s;
}

#include <iostream.h>
main()
{
int x,y;
cout<<"x=";
cin>>x;
if (x<=0) { //满足条件执行
y=2*x;
cout<<"y="<<y; //输出结果
}
else { //不满足条件执行
y=x*x;
cout<<"y="<<y; //输出结果
}
}
#include <iostream.h>
main()
{
int a,b,c;
int smallest;
cout<<"a b c"<<endl;
cin>>a>>b>>c;
if (a<=b) //外层条件语句
{
if (a<=c) //内层条件语句
smallest=a;
else
smallest=c;
}
else
{
if (b<=c) //内层条件语句
smallest=b;
else
smallest=c;
}
cout<<"Smallest="<<smallest<<endl;
}

#include <iostream.h>
main()
{
int score;

//从键盘上输入分数
cout<<"score=";
cin>>score;

//用带else if的条件语句判断处理
if (score<0 || score>100)
{
cout<<"The score is out of range!"<<endl;
}
else if (score>=90)
cout<<"Your grade is a A."<<endl;
else if (score>=80)
cout<<"Your grade is a B."<<endl;
else if (score>=70)
cout<<"Your grade is a C."<<endl;
else if (score>=60)
cout<<"Your grade is a D."<<endl;
else
cout<<"Your grade is a E."<<endl;
}
#include <iostream.h>
main()
{
int n;
cout<<"n=";
cin>>n;
if (n>=0 && n<=100 &&n%2==0)
cout<<"n="<<n<<endl;
else
cout<<"The "<<n<<" is out of range!"<<endl;
}

#include <iostream.h>
main()
{
int a,b,Max;
//输入数据
cout<<"a=";
cin>>a;
cout<<"b=";
cin>>b;

//找出较大值
Max=a>b?a:b;
cout<<"Max="<<Max<<endl;
}

#include <iostream.h>
main()
{
int a,b;
//输入数据
cout<<"a=";
cin>>a;
cout<<"b=";
cin>>b;

//除法判断
if (b!=0 && a%b==0) {
cout<<b<<" divides "<<a<<endl;
cout<<"a/b="<<a/b<<endl;
}
else
cout<<b<<" does not divide "<<a<<endl;
}

#include <iostream.h>
main()
{
//x,y 为操作数，c为运算符
int x,y,z;
char c1;
cin>>x>>c1>>y; //c1