C++:概述

1.基本的输入输出,使用cin>>输入输入、使用cout<<输出

#include<iostream>
using namespace std;
int main()
{
  int a,b,d,min;
  cout<<"Enter two numbers:"<<endl;
  cin>>a>>b;
  cout<<"min = "<<(min=a>b? b:a);
  for(d=;d<min;d++)
    if(((a%d)==) && ((b%d)==)) break;
  if (d==min)
   {
    cout<<"no common denominators"<<endl;
    return ;
   }
  cout<<"the lowest common denominator is"<<d<<endl;
  return ;
} 

Enter two numbers:

min =
the lowest common denominator is2
Program ended with exit code: 

2.使用引用,引用用地址符号&表示,引用就是给变量或者常量起的另一个别名,操作的还是同一个数据

//引用当做返回值

/*
需求：使用引用返回函数值
*/
#include<iostream>
using namespace std;
int &f(int &i)    //定义函数返回一个整数类型的引用，等价于返回数值i
{
 i+=;
 return i;
}
int main()
{
  int k=;
  int &m=f(k); //k=i=10
  cout<<k<<endl;
  m=;
  cout<<k<<endl;
  return ;
} 

Program ended with exit code: 

//引用当做参数

/*
 需求:引用作为函数参数
*/
#include<iostream>
using namespace std;
void f(int &m,int n)
{
 int temp;
 temp = m;
 m = n;
 n =temp;
}
int main()
{
 int a = ,b = ;
 cout<<"a = "<<a<<" "<<"b = "<<b<<endl;
 f(a,b);
 cout<<"a = "<<a<<" "<<"b = "<<b<<endl;
 return ;
} 

a =  b =
a =  b =
Program ended with exit code: 

3.使用作用域运算符::,作用变量或常量或函数的有效区域

/*
 需求：作用域运算符::
*/
#include<iostream>
using namespace std;
int i=;
int main ()
{
 int i;
 i = ;
 ::i = i+;
 cout<<i<<endl;
 cout<<::i<<endl;
 return ;
}

Program ended with exit code: 

4.结构体的简单使用,它有自己的属性成员和方法成员，需要创建结构体成员变量才能调用自己的属性和方法

//#include<iostream>
//#include<cmath>
//using namespace std;
#include<iostream.h>
#include<math.h>
struct Complex                 //声明一个名为Complex的结构体
{
 double real;                  //数据成员，复数的实部
 double imag;                  //数据成员，复数的虚部
 void init(double r,double i)  //成员函数init，给real和imag赋给初值
 {
  real = r;
  imag = i;
 }
 double abscomplex()           //成员函数，求复数的绝对值
 {
  double t;
  t = real*real+imag*imag;
  return sqrt(t);
 }
};
 int main()
 {
  Complex A;              //定义结构体Complex的成员变量A
  A.init(1.1,2.2);        //调用成员函数init，给real和imag赋给初值
  cout<<"复数的绝对值是:"<<A.abscomplex()<<endl; //调用成员函数abscomplex
  return ;
 }

复数的绝对值是:2.45967
Program ended with exit code: