一看就能懂的c++打印案例只属数学课堂范例了 - 信息发布软件,b2b软件,广告发布软件

设计一个编写仅包含C++程序基本构成元素的程序
/*    //注释行开始
This is the first C++ program.
Designed by zrf
*/    //注释行结束
#include <iostream> //包含头文件
using namespace std; //打开命名空间std
// This is the main function //单行注释语句
int main(void) //主函数，程序入口
{ //块作用域开始
int age;    //声明一个变量
age= 20;    //赋值语句
cout<<"The age is:\n"; //输出一个字符串
cout<<age<<endl;    //输出变量中的值
return 0;    //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>
using namespace std;
int main()
{ const float PI=3.1415926; //float 型常量
float r=2.0; //用float 型常量初始化变量
cout<<"r="<<r<<endl; //输出圆的半径
float length; //float型变量声明
length=2*PI*r; //计算圆的周长
cout<<"Length="<<length<<endl; //输出圆的周长
float area=PI*r*r; //计算圆的面积
cout<<"Area="<<area<<endl; //输出圆的面积
return 0;
}

【案例2-3】整数的简单运算——除法、求余运算法和增量减量运算符
#include <iostream>
using namespace std;
int main()
{ int x, y;
x = 10;  y = 3;
cout << x << " / " << y << " is " << x / y //整数的除法操作
<<" with x % y is " << 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
return 0;
}

【案例2-4】多重计数器——前置和后置自增运算符
#include<iostream>
using namespace std;
int main()
{ int iCount=1; iCount=(iCount++)+(iCount++)+(iCount++); //后置++
cout<<"The first  iCount="<<iCount<<endl;
iCount=1; iCount=(++iCount)+(++iCount)+(++iCount); //前置++
cout<<"The second iCount="<<iCount<<endl;
iCount=1; iCount=-iCount++; //后置++
cout<<"The third  iCount="<<iCount<<endl;
iCount=1; iCount=-++iCount; //前置++
cout<<"The fourth  iCount="<<iCount<<endl;
return 0;
}

【案例2-5】对整数“10”和“20”进行位运算——位运算的应用
#include <iostream>
using namespace std;
int main()
{ 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
return 0;
}

【案例2-6】实现逻辑“异或”运算——逻辑运算应用
#include <iostream>
using namespace std;
int main()
{ bool p, q;
p = true; q = true;
cout <<p <<" XOR "<<q<<" is "<<( (p || q) && !(p && q) )<< "\n"; //输出异或结果
p = false; q = true;
cout <<p<<" XOR "<<q<< " is "<<( (p || q) && !(p && q) )<< "\n"; //输出异或结果
p = true; q = false;
cout <<p<<" XOR "<<q<<" is "<<( (p || q) && !(p && q) )<< "\n"; //输出异或结果
p = false; q = false;
cout <<p<<" XOR "<<q<<" is "<<( (p || q) && !(p && q) )<< "\n"; //输出异或结果
return 0;
}

【案例2-7】高效筛选器——用条件运算符“?”构建条件表达式
#include<iostream>
using namespace std;
int main()
{ int iNum1=1,iNum2,iMax;
cout<<"lease input two integers:\n";
cin>>iNum1>>iNum2;
iMax = iNum1>iNum2 ? iNum1 : iNum2; //使用条件运算符构建条件表达式
cout<<"The max integer is: "<<iMax<<endl;
return 0;
}

【案例2-8】“多计算与单提取”功能的实现——逗号表达式
#include<iostream>
using namespace std;
int main()
{ int Val1, Val2, Val3, Left, Midd, Righ;
Left = 10; Midd = 20; Righ = 30;
Val1 = (Left++, --Midd, Righ++); //使用逗号表达式
Val2 = (Righ++, Left++, --Midd); //使用逗号表达式
Val3 = ( --Midd, Righ++,Left++); //使用逗号表达式
cout <<"Val1=\t"<<Val1 <<"\nVal2=\t"<<Val2 <<"\nVal3=\t"<<Val3<<endl;
return 0;
}

【案例2-9】高效的算术运算符——复合赋值运算符
#include <iostream>
using namespace std;
int main()
{ int n=20;  cout << "n = " << n << endl;
n += 8; cout << "After n += 8, n = " << n << endl;  //使用复合的赋值运算符+=
n -= 6; cout << "After n -= 6, n = " << n << endl;  //使用复合的赋值运算符-=
n *= 1; cout << "After n *= 1, n = " << n << endl; //使用复合的赋值运算符*=
n /= 4; cout << "After n /= 4, n = " << n << endl;  //使用复合的赋值运算符/=
n %= 3;  cout << "After n %= 3, n = " << n << endl;  //使用复合的赋值运算符%=
return 0;
}

【案例2-10】计算不同数据类型的存储容量——sizeof运算符
#include <iostream>
using namespace std ;
int main()
{ cout << "The size of an int is:\t\t" << sizeof(int) << " bytes.\n";
cout << "The size of a short int is:\t" << sizeof(short) << " bytes.\n";
cout << "The size of a long int is:\t" << sizeof(long) << " bytes.\n";
cout << "The size of a char is:\t\t" << sizeof(char) << " bytes.\n";
cout << "The size of a wchar_t is:\t" << sizeof(wchar_t) << " bytes.\n";
cout << "The size of a float is:\t\t" << sizeof(float) << " bytes.\n";
cout << "The size of a double is:\t" << sizeof(double) << " bytes.\n";
return 0;
}

【案例2-11】巧妙获取整数部分——double和int数据类型的转换
#include <iostream>
using namespace std;
int main()
{ int nn=10,mm;
double xx=4.741,yy;
cout<<"nn*xx="<<nn*xx<<endl;    //表达式类型转换
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
return 0;
}

【案例2-12】将分数转换为小数——强制类型转换
#include <iostream>
using namespace std;
int main()
{ for( int i=1; i <= 5; ++i )
cout << i << "/ 3 is: " << (float) i / 3 << endl; //强制类型转换
return 0;
}

【案例2-13】安全的除法计算器
#include <iostream>
using namespace std;
int main()
{ int a, b;
cout << "Enter numerator: "; cin >> a;
cout << "Enter denominator: "; cin >> b;
if(b) cout << "Divide Result is: " << a / b << '\n'; //排除除数为零的情况
else cout << "Divide by zero!\n";
return 0;
}

【案例2-14】猜数游戏——嵌套的if条件语句
#include <iostream>
#include <cstdlib>
using namespace std;
int main()
{ int MagNum, GueNum;
MagNum = rand();    //产生随机数
cout << "Enter the Guess number: "; cin >> GueNum;
if (GueNum == MagNum)
{       //if语句块起始位置
  cout << "* It is Right *\n"<< MagNum << " is the Magess number.\n";
}    //if语句块结束位置
else
{       // else语句块起始位置
  cout << "Sorry, you're wrong."<<endl;
  if(GueNum > MagNum)
   cout <<"Guessed number is too high.\n";
  else
   cout << "Guessed number is too low.\n";
}       //else语句块结束位置
return 0;
}

【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>
using namespace std;
int main()
{ int year,month,days=0;
cout<<"Input year and month:";  cin>>year>>month;
switch (month)    //每个case分支均没有break语句
{ case 12: days +=31;
  case 11: days +=30;
  case 10: 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:    //判断是否为闰年
if (year % 4==0 && year % 100!=0 || year %400==0)
         days +=29;
else
         days +=28;
  case  1: days +=31;
}
if (days==0) cout<< "Wrong month"<<endl;
else    cout << "Total days is:" <<days<< endl;
return 0;
}

【案例2-16】计算数的阶乘——do-while循环语句
#include <iostream>
using namespace std;
int main()
{  long limits;
cout << "Enter a positive integer: "; cin >> limits;
cout << "Factorial numbers of "<<0<<" is " << 1<<endl;
cout << "Factorial numbers of "<<1<<" is " << 1<<endl;
long fac=1, i=1;
do    //使用do-while循环
{  fac *= ++i;
   cout << "Factorial numbers of "<<i<<" is " << fac<<endl;
} while (fac < limits);
return 0;
}

【案例2-17】计算数的阶乘——for循环
#include <iostream>
using namespace std;
int main()
{ long limits;
cout << "Enter a positive integer: "; cin >> limits;
cout << "Factorial numbers of "<<0<<" is " << 1<<endl;
cout << "Factorial numbers of "<<1<<" is " << 1<<endl;
long fac=1;
for(int i=2;fac<=limits;i++) //使用for 循环
{ fac *= i;
cout << "Factorial numbers of "<<i<<" is " << fac<<endl;
}
return 0;
}

【案例2-18】筛选素数——步长为2的for循环
#include <iostream>
#include <cstdlib>
using namespace std;
int main()
{ long n;
cout << "Enter a positive integer: ";  cin >> n;
if (n < 2)
   cout << n << " is not prime." << endl;
else if (n < 4)
   cout << n << " is prime." << endl;
else if (n%2 == 0)
   cout << n << " = 2*" << n/2 << endl;
else
{ for (int i=3; i <= n/2; i += 2)  //步长为2
if (n%i == 0)
      {cout << n << " = " << i << "*" << n/i << endl;  exit(0);}
  cout << n << " is prime." << endl;
}
return 0;
}

【案例2-19】输出1~20之间的偶数——continue语句
#include <iostream>
using namespace std;
int main()
{ cout<<"The even numbers are as follows:"<<endl;
for(int i=0; i<=20; i++)
{ if(i%2) continue; //根据条件使用continue结束本次循环
cout << i << ' ';
}
return 0;
}

【案例2-20】统计输入整数的个数并求和——exit()函数
#include <iostream>
#include <cstdlib>
using namespace std;
int main()
{ int sum=0,num=0,m;
cout<<"lease input integers (0:end):"<<endl;
do { cin>>m; num++; sum+=m;
   if(m==0)
   { cout<<"Entered numbers:"<<num<<" integers.\n";
cout<<"The sum is:"<<sum<<endl;
exit(0); // 使用exit()函数终止程序
   }
}while(1);
return 0;
}

【案例2-21】“剪刀、石头、布”游戏——枚举类型
#include <iostream>
using namespace std;
enum Choice {ROCK, CLOTH, SCISS}; //声明枚举类型Choice
enum Winner {Play1, Play2, Tie}; //声明枚举类型Winner
int main()
{ int n;
Choice cho1, cho2;
Winner winner;
cout << "Choose rock (0), cloth (1), or Sciss (2):" << endl;
cout << "layer No. 1: "; cin >> n; cho1 = Choice(n);
cout << "layer No. 2: "; cin >> n; cho2 = Choice(n);
if (cho1 == cho2) winner = Tie;
else if (cho1 == ROCK)
  if (cho2 == CLOTH)  winner = Play2;
  else  winner = Play1;
else if (cho1 == CLOTH)
  if (cho2 == SCISS)  winner = Play2;
  else  winner = Play1;
else
  if (cho2 == ROCK)  winner = Play2;
  else  winner = Play1;
if (winner == Tie) cout << "\tTied!\n";
else if (winner == Play1)  cout << "\tPlayer No. 1 wins." <<endl;
else  cout << "\tPlayer No. 2 wins." << endl;
return 0;
}

【案例2-22】简单的学生信息类型——结构体
#include <iostream>
#include <iomanip>
using namespace std;
struct student          //学生信息结构体
{ int num;
char name[20];
char gender;
int age;
}stu1={1001,"Zhang San",'M',19};
int main()
{ student stu2={1002,"Li Si",'M',20};  //声明结构体变量并初始化
student stu3={1003,"Wang Hong",'F',22};       //声明结构体变量并初始化
cout<<setw(7)<<stu1.num<<setw(20)<<stu1.name<<setw(3)<<stu1.gender<<setw(3)<<stu1.age<<endl;
cout<<setw(7)<<stu2.num<<setw(20)<<stu2.name<<setw(3)<<stu2.gender<<setw(3)<<stu2.age<<endl;
cout<<setw(7)<<stu3.num<<setw(20)<<stu3.name<<setw(3)<<stu3.gender<<setw(3)<<stu3.age<<endl;
return 0;
}

【案例2-23】综合案例——百钱买百鸡问题
#include<iostream>
using namespace std;
int main()
{
int n=100;
cout<<"鸡公  鸡母  鸡雏"<<endl;    //i表示鸡公，j表示鸡母，k表示鸡雏
for ( int i = 1; i <= n; i++ )
for ( int j = 1; j <= n; j++ )
for( int k = 1; k <= n; k++ )
   if(( n == 5 * i + 3 * j + k / 3 ) && ( k % 3 == 0 ) && ( n == i + j + k ))
   cout << i << "  " << j << "  " << k << endl;
return 0;
}

#include<stdio.h>
int main()
{
int x,y,z,j=0;
printf("Folleing are possible plans to buy 100 fowls with 100 Yuan.\n");
for(x=0;x<=20;x++)       //外层循环控制鸡翁数
   for(y=0;y<=33;y++)    //内层循环控制鸡母数y在0~33变化
   {
      z=100-x-y;          //内外层循环控制下，鸡雏数z的值受x,y的值的制约
      if(z%3==0&&5*x+3*y+z/3==100)       //验证取z值的合理性及得到一组解的合理性
            printf("%2d:cock=%2d hen=%2d chicken=%2d\n",++j,x,y,z);
   }
}

【案例3-1】编写输出专用函数——无参函数
#include<iostream>
using namespace std;
void DispMessage(void)                   //定义无参函数
{
cout<<"This is a Message!"<<endl;
}
int main()
{
DispMessage();                         //调用无参函数DispMessage
return 0;
}

【案例3-2】编写求和函数——有参函数
#include<iostream>
using namespace std;
double add(double x,double y) //定义有参函数
{
double z; z=x+y; return(z);
}
int main()
{
double a=0.5, b=1.0;
cout<<"add(a,b)="<<add(a,b)<<endl; //调用有参函数add()
return 0;
}

【案例3-3】编写求和函数——函数的不同调用形式
#include<iostream>
using namespace std;
double add(double x,double y)                   //函数的定义，其有返回值
{
double z; z=x+y;
cout<<x<<"+"<<y<<"="<<z<<endl;
return(z);
}
int main()
{
double a=0.5,b=1.0;
//以不同参数形式调用函数add()
cout<<"add(1.5,2.5)="<<add(1.5,2.5)<<endl;
cout<<"add(a,b)="<<add(a,b)<<endl;
cout<<"add(2*a,a+b)="<<add(2*a,a+b)<<endl;
double c=2*add(a,b);                                  //以表达式方式调用函数add()
cout<<"c="<<c<<endl;
add(2*a,b);                                                    //以语句方式调用函数add()
cout<<" add(a, add(a,b))="<<add(a, add(a,b))<<endl;    //以函数参数形式调用函数add()
return 0;
}

【案例3-4】编写符号函数——函数的返回值
#include<iostream>
using namespace std;
int sgn(double x)                      //定义符号函数sgn()，其返回值为int类型
{
if (x>0) return(1);                //返回出口1
if (x<0) return(-1);             //返回出口2
return(0);                            //返回出口3
}
int main()
{
double x;
for (int i=0;i<=2;i++)
{
   cout<<"Input x=";    cin>>x;
   cout<<"sgn("<<x<<")="<<sgn(x)<<endl;
}
return 0;
}

【案例3-5】编写最值函数——函数原型声明
#include<iostream>
using namespace std;
//…函数原型声明语句也可以在这里
int main()
{
float max(float,float);                         //max()函数原型声明语句
float a,b,Max;                                     //变量声明语句
cout<<" Input a="; cin>>a;             //输入参数a
cout<<" Input b="; cin>>b;          //输入参数b
Max=max(a,b);                               //调用max()函数
cout<<"max("<<a<<","<<b<<")="<<Max<<endl;
return 0;
}
float max(float x,float y) {
float z; z=(x>y)?x:y;
return(z);                                        //返回值类型为浮点型
}

【案例3-6】值传递和引用传递的区别
#include <iostream>
using namespace std;
void fun(int,int&); //函数参数一个为值传递，一个引用传递
int main()
{
int a = 22, b = 44;
cout << "Initial a = " << a << ", b = " << b << endl;
fun(a,b); cout << "After fun(a,b), a = " << a << ", b = " << b << endl;
fun(2*a-3,b); cout << "After fun(2*a-3,b), a = " << a << ", b = " << b << endl;
return 0;
}
void fun(int x, int& y)
{
x = 88; y = 99;
}

【案例3-7】编写最值函数——内联函数
#include<iostream>
using namespace std;
inline int max(int x,int y) //使用inline关键字声明max()为内联函数
{
return x>y?x:y;
}
int main()
{
int a=3,b=5,c;
c=max(a,b); cout<<"max("<<a<<","<<b<<")="<<c<<endl;
cout<<"max("<<15<<","<<11<<")="<<max(15,11)<<endl;
return 0;
}

【案例3-8】计算圆的面积和周长函数——通过引用返回多于1个的数值
#include <iostream>
using namespace std;
void ComCircle(double&, double&, double);          //函数的原型声明
int main()
{
double r, a, c;
cout << "Enter radius: ";  cin >> r;
ComCircle(a, c, r);
cout << "The area = " << a << ", and the circumference = " << c << endl;
return 0;
}
void ComCircle(double& area, double& circum, double r)       //通过引用变量返回面积和周长
{
const double PI = 3.141592653589793;
area = PI*r*r;  circum = 2*PI*r;                                        //计算面积和周长
}

【案例3-9】最小公倍数函数——函数的嵌套调用
#include <iostream>
using namespace std;
long int gcd(long int m,long int n)                            //求最大公约数
{
if (m < n) swap(m,n);
while (n>0)
      {
         int r = m%n; m = n; n = r;
      }
return m;
}
long int lcm(long int m,long int n)                         //求最小公倍数
{
return m*n/gcd(m,n);
}
int main()
{
int m, n;
cout << "

lease input two integers: "; cin >> m >> n;
cout << "lcm(" << m << "," << n << ") = " << lcm(m,n) << endl;
return 0;
}

【案例3-10】显示函数的参数——带默认参数的函数
#include <iostream>
using namespace std;
void disp(int x=1,int y=1,int z=1) //带有默认参数值的函数
{
cout<<"

arameter 1 is: "<<x<<endl;
cout<<"

arameter 2 is: "<<y<<endl;
cout<<"

arameter 3 is: "<<z<<endl;
}
int main() //main()函数中测试参数带有默认值的函数disp()
{
cout<<"No actual parameter"<<endl; disp();
cout<<"One actual parameter"<<endl; disp(1);
cout<<"Two actual parameter"<<endl; disp(1,2);
cout<<"Three actual parameter"<<endl; disp(1,2,3);
return 0;
}

【案例3-11】通用最值函数——参数数目可变的函数
#include <iostream>
#include <cstdarg>
using namespace std;
int max(int,int...);                               //原型声明
int main()
{
int a,b,c,d,e;
cout<<"Enter five integers, seperate with space:"; cin>>a>>b>>c>>d>>e;
cout<<"The maxmum in a and b is:"<<max(2,a,b)<<endl;
cout<<"The maxmum in five integers is:"<<max(5,a,b,c,d,e)<<endl;
return 0;
}
int max(int num,int integer...)          //定义参数数目可变的函数
{
va_list ap;
int n=integer;
va_start(ap,integer);
for(int i=1;i<num;i++)
{
int t=va_arg(ap,int);
if(t>n)
         n=t;
}
va_end(ap);
return n;
}

【案例3-12】多变的最值函数——参数数目不同的重载函数
#include <iostream>
using namespace std;
int main()
{
int min (int a, int b, int c);                      //函数声明
int min (int a, int b);                               //函数声明
int i1 ,i2,i3,i;
cout<<"Enter three integers:"; cin >>i1 >>i2 >>i3;                   //输入3个整数
i = min(i1 ,i2) ;  cout <<"The min in two intergers=" <<i <<endl;    // 2个整数中最小者
i = min(i1 ,i2 ,i3) ;                               // 3个整数中最小者
cout <<"The min in three intergers=" <<i <<endl;
return 0;
}
int min(int a,int b,int c)                            //定义求3个整数中的最小者的函数
{
int k;
k=(a<b)?a:b;
k=(k<c)?k:c;
return k;
}
int min(int a,int b)                                  //定义求2个整数中的最小者的函数
{
int k;
k=(a<b)?a:b;
return k;
}

【案例3-13】求绝对值——使用系统函数
#include <iostream>
#include <cmath>
#include <cstdlib>
using namespace std;
void main( void )
{
int ix = -4, iy;
long lx = -41567L, ly;
double dx = -3.141593, dy;
iy = abs( ix ); cout<<"The absolute value of"<<ix <<" is "<<iy<<endl;
ly = labs( lx ); cout<<"The absolute value of"<<lx <<" is "<<ly<<endl;
dy = fabs( dx ); cout<<"The absolute value of"<<dx <<" is "<<dy<<endl;
}

【案例3-14】将整数和小数分离——使用系统函数
#include<iostream>
#include<cmath>
using namespace std;
void main(void)
{
double fraction, integer,number = 103.567;
fraction = modf(number, &integer);
cout<<number<<"整数部分为:"<<integer<<" 小数部分为:"<<fraction;
}

【案例3-15】求平方根——使用系统函数
#include <iostream>
#include <cmath>
#include <cstdlib>
using namespace std;
void main( void )
{
double question = 45.35, answer;
answer = sqrt( question );
if( question < 0 )
cout<<"Error: sqrt returns "<<answer<<endl;
else
cout<<"The square root of "<<question<<" is "<<answer<<endl;
}

【案例3-16】求随机数——使用系统函数
#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;
void main(void)
{
cout << "RAND_MAX=" << RAND_MAX << endl;
cout<<"产生10个 0 到 99的随机数如下:\n";
for(int i=0; i<10; i++)
cout<<(rand() % 100)<<' '; //求除以100的余数
cout << "\n使用srand:\n";
srand( (unsigned)time( NULL ) );
for( i = 0; i < 10;i++ )
cout<<rand() <<' ';
}

【案例3-17】计算时间差——使用系统函数
#include <iostream >
#include <ctime >
#include <conio.h>
using namespace std;
void main(void)
{
time_t start,end;
start = time(NULL);
cout << "请按Enter键!\n";
for (;;)
{
      if (getch()=='\r')
         break;
}
end = time(NULL);
cout << "按键前后相差:"<<difftime(end,start)<<" 秒";
}

【案例4-1】编写设计全部成员为public模式的类
#include<iostream>
using namespace std;
class PubClass
{public:                                                       //以下成员均为公有成员
int value;                                                 //公有数据成员
void set(int n)                                        //公有函数成员
{
      value=n;
}
int get(void)                                           //公有函数成员
{
      return value;
}
};
int main()
{
PubClass a;                                                             //创建对象
a.set(10); cout<<"a.get()="<<a.get()<<endl;             //直接访问对象的公有成员函数
a.value=20; cout<<"a.value="<<a.value<<endl;    //直接访问对象的公有数据成员
return 0;
}

【案例4-2】编写设计private数据访问模式的类
#include <iostream>
using namespace std;
class PriClass
{
int iv; double dv;                                        //私有数据成员
public:
void set_PriClass(int n,double x);          //公有函数成员为接口函数
void show_PriClass(char*);                   //公有函数成员为接口函数
};
//定义PriClass类的接口成员函数
void PriClass::set_PriClass(int n,double x) { iv=n;  dv=x;}
void PriClass::show_PriClass(char *name)
{
cout<<name<<": "<<"iv=" <<iv<< ", dv=" <<dv<< endl;
}
int main()
{
PriClass obj;
obj.show_PriClass("obj");                         //通过接口函数来访问数据成员
obj.set_PriClass(5,5.5);  obj.show_PriClass("obj");    //通过接口函数来访问数据成员
return 0;
}

【案例4-3】编写结构体类——以结构体形式定义类
说明：结构体和类唯一区别是：结构体成员的访问权限默认为公有的，而类成员的访问权限默认为私有的

#include<iostream>
using namespace std;
struct StructClass                            //用struct关键字定义StructClass类
{
void set_value(int n)                                  //公有属性
{
      value=n;
}
void show_value(char *name)                //公有属性
{
      cout<<name<<": "<<value<<endl;
}
private:                               //为了保持私有属性，不能省略private
int value;
};
int main()
{
StructClass a;
a.show_value ("a");                               //通过对象访问公有属性函数
a.set_value(100);
a.show_value ("a");                               //通过对象访问公有属性函数
return 0;
}

【案例4-4】完善有理数类——拷贝构造函数的调用时机
#include <iostream>
using namespace std;
int gcd(int m, int n)                                     //返回m 和n最大公约数
{
if (m<n)  swap(m,n);
while (n>0)  { int r=m%n; m = n; n = r;  }
return m;
}

class Ratio
{
public:
Ratio(int n=0, int d=1) : num(n), den(d)
{
      cout << "Common constructor called\n"; reduce();
}
Ratio(const Ratio& r):num(r.num), den(r.den)                      //拷贝构造函数
{
      cout << "Copy constructor called\n";
}
void disp()
{
      cout <<num<<"/"<<den<<endl;
}
private:
int num, den;
void reduce()
{
      if (num == 0 || den == 0)
      {
      num = 0; den = 1; return; }
   if (den < 0) {den *= -1; num *= -1; }
   if (den == 1) return;
   int sgn = (num<0?-1:1);  int g = gcd(sgn*num,den);
   num /= g;  den /= g;
  }
};
Ratio func(Ratio r)                                     //初始化形参时调用拷贝构造函数
{
Ratio s = r;
return s;                                                    //返回时调用拷贝构造函数
}
int main()
{
Ratio x(20,7);
cout<<"Ratio x is:"; x.disp();
Ratio y(x);                                     //调用拷贝构造函数，用x初始化y
cout<<"Ratio y is:"; y.disp();
cout<<"Func() Start:"<<endl;
func(y);                                              //调用拷贝构造函数3次
cout<<"Func() End"<<endl;
return 0;
}

【案例4-5】完善的有理数类——析构函数
#include <iostream>
using namespace std;
class Ratio
{
int num, den;
public:
   Ratio()       {cout << "Constructor called.\n";}
   Ratio(Ratio &r)  { cout << "Copy constructor called.\n"; }
   ~Ratio()       { cout << "Destructor called.\n"; }
};
int main()
{
Ratio x;
{                                     //x的作用域开始
      Ratio y;                            //y的作用域开始
cout << "Now y is alive.\n";
}                                        //y的作用域结束，调用析构函数1次
cout << "Now between blocks.\n";
{
      Ratio z(x);                               //z的作用域开始
      cout << "Now z is alive.\n";
}                                                 //z的作用域结束，调用析构函数1次
return 0;
}

//x的作用域结束，调用析构函数1次

【案例4-6】综合案例——电子日历
#include <iostream >
#include <cstdlib >
using namespace std;
class CDate                                                                //定义电子日历类
{
int m_nDay;  int m_nMonth;  int m_nYear;          //日月年
public:
CDate(){};                                                             //默认构造函数
CDate(int year, int month,int day )                      //带参构造函数
{
      SetDate(year, month, day);                               //调用成员函数来初始化
};
void Display();    //显示日期
void AddDay();    //返回加1后的日期
void SetDate(int year, int month, int day)             //设置日期
{
      m_nDay=day; m_nMonth=month;    m_nYear=year;
}
~CDate() {};
private:
bool IsLeapYear() ;                                              //判断是否为闰年
};
void CDate:

isplay()                                           //显示日期
{
char day[5] ,month[5], year[5] ;
_itoa (m_nDay, day, 10) ;
_itoa (m_nMonth, month, 10) ;
_itoa(m_nYear,year, 10) ;
cout << day << "/" << month << "/" << year << endl;
}
void CDate::AddDay ()                                           //返回加1后的日期
{
m_nDay++;
if (IsLeapYear())
{
      if ((m_nMonth==2) && (m_nDay==30))
      {
         m_nMonth++;
m_nDay=1;
return;
      }
}
else
{
      if((m_nMonth==2)&& (m_nDay==29))
      {
         m_nMonth++;
m_nDay=1;
return;
      }
}
if (m_nDay>31 )
{
      if(m_nMonth==12)  { m_nYear++; m_nMonth=1 ; m_nDay=1 ;  }
      else  { m_nMonth++;  m_nDay=1 ; }
}
}
bool CDate::IsLeapYear()                                     //判断是否为闰年
{
bool bLeap;
if(m_nYear%4!=0)                   bLeap=false;
else if(m_nYear%100!=0)    bLeap=true;
else if(m_nYear%400!=0)    bLeap=false;
else             bLeap=true;
return bLeap;
}
void main ()
{
CDate d (2010,4,6);                                           //调用构造函数初始化日期
cout << "Current date:";
d.Display();
d.AddDay();
cout << "Add 1 to Current date:";
d.Display();
d. SetDate(2010,4,8);                                        //调用成员函数重新设置日期
cout << "After reset Date,the date:";
d.Display();
}

【案例5-1】局部作用域的效果
#include <iostream>
using namespace std;
void fun()                         //变量num将在每次进入函数fun()时进行初始化
{
   int num = 10;
   cout << num << "\n";
   num++;                      // 这个语句没有持续效果
}
int main()
{
   for(int i=0; i < 3; i++)
      fun();
   return 0;
}

【案例5-2】屏蔽效应——作用域效果导致的名称隐藏
#include <iostream>
using namespace std;
int main()
{
   int i = 10, j = 30;
   if(j > 0)
   {
      int i;                   // 内部的i 将隐藏或屏蔽外层的i
   i = j / 2;
      cout << "inner variable i: " << i << '\n';
   }
   cout << "outer variable i: " << i << '\n';
   return 0;
}

【案例5-3】筛选偶数——文件作用域变量
#include <iostream>
using namespace std;
int count;                //这是一个全局变量
void func1()
{
   void func2();
   cout << "count: " << count<< '\n'; //可以访问全局变量count
   func2();
}
void func2()
{
   int count;    //这是一个局部变量
   for(count=0; count<2; count++)
      cout << '*';
}
int main()
{
   void func1();
   void func2();
   int i;    //这是一个局部变量
   for(i=0; i<10; i++)
   {
      count = i++;
      func1();
   }
   return 0;
}

【案例5-4】求数据序列的平均值——static局部变量的持续效果
#include <iostream>
using namespace std;
int Average(int i)
{
   static int sum = 0, count = 0;          //声明静态局部变量，具有全局寿命，局部可见
   sum = sum + i; count++;
   return sum/count;
}
int main()
{
   int num;                               //局部变量，具有动态生存期
do
{
         cout << "Enter numbers (-1 to quit): ";    cin >> num;
   if(num != -1)
               cout << "Running average is: " << Average(num);
   cout <<endl;
} while(num > -1);
return 0;
}

【案例5-5】求数据序列的平均值——static全局变量的应用
#include <iostream>
using namespace std;
int Average(int i);
void reset();
int main()
{
   int num;    //局部变量，具有动态生存期
   do
   {
      cout << "Enter numbers (-1 to quit, -2 to reset): ";
      cin >> num;
if(num == -2)
      {
            reset();
            continue;
      }
if(num != -1)
            cout << "Running average is: " << Average(num);
cout << endl;
   } while(num != -1);
   return 0;
}
static int sum = 0, count = 0;                //静态全局变量，具有静态生存期，全局可见
int Average(int i)
{
   sum = sum + i;  count++;  return sum/count;
}
void reset()
{
   sum = 0; count = 0;
}

【案例5-6】时钟类——具有静态生存期的全局变量和全局对象
#include<iostream>
using namespace std;
int h=0,m=0,s=0;                //声明全局变量，具有静态生存期
class Clock
{
public:
   Clock();
   void SetTime(int NewH, int NewM, int NewS);    //三个形参均具有函数原型作用域
   void ShowTime();
   ~Clock(){}
private:
   int Hour,Minute,Second;
};
Clock::Clock()
{
   Hour=h; Minute=m; Second=s;                   //使用全局变量初始化
}
void Clock::SetTime(int NewH, int NewM, int NewS)
{
   Hour=NewH;  Minute=NewM; Second=NewS;
}
void Clock::ShowTime()
{
   cout<<Hour<<":"<<Minute<<":"<<Second<<endl;
}
Clock globClock;                            //声明对象globClock，具有静态生存期，文件作用域
int main()
{
   cout<<"Initial time output:"<<endl;
   //引用具有文件作用域的对象globClock：
   globClock.ShowTime();          //对象的成员函数具有类作用域
   globClock.SetTime(10,20,30);          //将时间设置为10:20:30
   //调用拷贝构造函数，以globClock为初始值
   Clock myClock(globClock);                   //声明具有块作用域的对象myClock
   cout<<"Setted time output:"<<endl;
   myClock.ShowTime(); //引用具有块作用域的对象myClock
   return 0;
}

【案例5-7】实现数据共享——公有静态数据成员
#include <iostream>
using namespace std;
class PubClass
{
public:
   static int num;          //公有静态数据成员的声明
   void shownum() { cout << "The num is:"<<num << endl; }
};
int PubClass::num;          //在类外定义num
int main()
{
   PubClass a, b;
   PubClass::num = 1000;          //通过类名访问静态成员num
   a.shownum();
   b.shownum();
   a.num = 2000;             //通过对象访问静态成员num
   a.shownum();
   b.shownum();
   return 0;
}

【案例5-8】实现数据共享——私有型静态数据成员
#include <iostream>
using namespace std;
class PriClass
{
   static int num;       //私有型静态成员
public:
   void setnum(int i) { num = i; };
   void shownum() { cout << "The num is:"<<num << "\n"; }
};
int PriClass::num;    //在类外定义 num
int main()
{
   PriClass a, b;
   a.shownum(); b.shownum();
   a.setnum(1000);    //设置静态成员num为1000
   a.shownum(); b.shownum();
   return 0;
}

【案例5-9】实现函数共享——静态函数成员
#include <iostream>
using namespace std;
class FunClass
{
   static int count;    //静态数据成员声明
public:
   FunClass() { count++; cout << "Constructing object " <<count << endl; }
   ~FunClass() { cout << "Destroying object " << count << endl;    count--; }
   static int GetCount() { return count; }    //静态函数成员
};
int FunClass::count;    //静态数据成员定义
int main()
{
   FunClass a, b, c;
   cout << "From Class, there are now " << FunClass::GetCount() << " in existence.\n";
   cout << "From Object, there are now " << a.GetCount() <<" in existence.\n";
   return 0;
}

【案例5-10】求最小公因子——友元函数的访问类的私有成员
#include <iostream>
using namespace std;
class FriFunClass
{
   int a, b;
public:
   FriFunClass(int i, int j) { a=i; b=j; }
   friend int FriFun(FriFunClass x);       //友元成员函数
};
int FriFun(FriFunClass x)       //注意：FriFun() 不是任何类的成员函数
{
   //由于函数FriFun() 是类FriFunClass的友元函数，所以它不能直接访问a和b
   int max = x.a < x.b ? x.a : x.b;
   for(int i=2; i <= max; i++)
      if((x.a%i)==0 && (x.b%i)==0)
            return i;
   return 0;
}
int main()
{
   FriFunClass n(10, 20);       //声明类对象
   if(FriFun(n))
      cout << "Common denominator is " <<FriFun(n) << "\n";
   else  cout << "No common denominator.\n";
return 0;
}

【案例5-11】判断圆柱体和立方体的颜色是否相同——多个类共享友元函数
#include <iostream>
using namespace std;
class Cylinder;       // 前向引用声明
enum Colors { red, green, yellow };    //定义颜色枚举类型
class Cube
{
Colors color;
public:
   Cube(Colors c) { color = c; }
   friend bool TestSame(Cube x, Cylinder y);    //声明为Cube的友元函数
};
class Cylinder
{
Colors color;
public:
   Cylinder(Colors c) { color= c; }
   friend bool TestSame(Cube x, Cylinder y);    //声明为Cylinder的友元函数
};
bool TestSame(Cube x, Cylinder y)
{
   if(x.color == y.color)
      return true;
   else return false;
}
int main()
{
   Cube cube1(red),  cube2(yellow);
   Cylinder cyl(yellow);                      //声明对象并初始化
   if(TestSame(cube1, cyl))
      cout << "The color of cube1 and cyl are the same.\n";
   else
      cout << "The color of cube1 and cyl are different.\n";
   if(TestSame(cube2, cyl))
      cout << "The color of cube2 and cyl are the same.\n";
   else
      cout << "The color of cube2 and cyl are different.\n";
   return 0;
}

【案例5-12】计算2个三角形之和——友元函数的应用一看就能懂的c++打印案例只属数学课堂范例了
#include <iostream>
#include <cmath>
using namespace std;
class Trig
{
   double  x,y,z;
   double area()  {double d=(x+y+z)/2;  return sqrt(d* (d-x)* (d-y)* (d-z)) ; }
public :
   Trig (int i,int j,int k)  { x=i;y=j;z=k;  }
   int isTriangle()       //判断是否构成三角形
   {
      if  (x+y>z && x+z>y && y+z>x)
            return 1 ;
else
            return 0;
   }
   friend  double twoarea(Trig tl,Trig t2)          //声明友元函数
   {
      return tl.area()+t2.area() ;
   }
};
int main()
{
   Trig tl (3,5,7) ,t2 (8, 7, 12) ;
   if (tl.isTriangle() && t2.isTriangle())
      cout << "Total area of two Triangles:" << twoarea(tl,t2)  << endl;
   else
      cout << "Cannot form a Triangle"<< endl;
   return 0;
}

【案例5-13】数据的单向传递——常引用作函数形参
#include <iostream>
using namespace std;
//常引用作形参，在函数中不能更新z所引用的对象，因此对应的实参不会被破坏。
void fun(int x, int& y, const int& z)
{
   x += z;
   y += z;
   cout << "x = " << x << ", y = " << y << ", z = " << z << endl;
}
int main()
{
   int a = 20, b = 30, c = 40;
   cout << "a = " << a << ", b = " << b << ", c = " << c << endl;
   fun(a,b,c);
   cout << "a = " << a << ", b = " << b << ", c = " << c << endl;
   fun(2*a-3,b,c);
   cout << "a = " << a << ", b = " << b << ", c = " << c << endl;
   return 0;
}

【案例5-14】成员函数的选择调用——常成员函数
#include<iostream>
using namespace std;
class ZRF
{
public:
   ZRF(int Z1, int Z2){ZRF1=Z1;ZRF2=Z2;}
   void disp();
   void disp() const;                         //常成员函数声明
private:
   int ZRF1,ZRF2;
};
void ZRF::disp()
{
   cout<<ZRF1<<":"<<ZRF2<<endl;
}
void ZRF::disp() const    //常成员函数定义
{
cout<<ZRF1<<":"<<ZRF2<<endl;
}
int main()
{
   ZRF a(2,3);
   a.disp();                                  //调用void disp()
   const ZRF b(10,20);
   b.disp();                                  //调用void disp() const
return 0;
}

【案例5-15】计算圆周长——不带参数的宏定义
#include<iostream>
using namespace std;
#define PI 3.14159                      //宏名PI为符号常量
#define n a                               //宏名n将用a来替换
#define LENGTH  2*PI*n                   // 宏名LENGTH将用2*PI*n来替换
int main()
{
   int n=1;                            //int n=1;替换为int a=1;
   cout<<"LENGTH="<<LENGTH<<endl;       //替换为cout<<"LENGTH="<<2*3.14159*a<<endl;

作者: lalajie 时间: 2017-6-27 14:25
这次合作，整个过程很顺利，今后我的店铺还是会请你帮我装修，希望越来越好

作者: niubt 时间: 2017-6-30 12:28
用，和卖家介绍的一样，操作简单，一学就会，满意。

作者: ebxly 时间: 2017-7-2 11:56
很厉害，5分钟就带我搞完了，很满意！客服态度也很好，以后有需要，还会找你们

作者: jskf10 时间: 2017-7-9 13:27
不错不错，您辛苦了。。。

作者: wangliuh11 时间: 2017-7-13 02:23
小手一抖，钱钱到手！

作者: niubt 时间: 2017-7-13 06:05
事情好垃圾的

作者: q117971371 时间: 2017-7-13 06:26
好很喜欢

作者: 261741908 时间: 2017-7-13 07:05
大气漂亮，全5星好评，已经合作好几次了，非常不错.

作者: ziyang701 时间: 2017-7-20 03:52
码，卖家发货也很快，5分好评！

作者: weipinzongmeng 时间: 2017-7-20 09:46
有耐心，下次还会找这家，都给我改了好几次了，就是时间比较长，等不起啊。总体还是很满意

作者: iiiiik 时间: 2017-7-20 09:51
谢谢，共同发展

作者: 阿拉丁 时间: 2017-7-20 10:55
错效率很高价格合理还会来的

作者: yerface 时间: 2017-7-21 23:06
这是什么东东啊

作者: a5206662 时间: 2017-7-23 21:56
模板物超所值！！！！！

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