C++学习笔记1

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分类专栏： C++学习笔记文章标签： c++ parameters delete 编译器 function

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一，类的最基本的函数

一个类至少有默认构造函数,拷贝构造函数，拷贝构造运算符，和析构函数四个最基本的函数，在下面的例子中将对这些函数进行讲解。

代码如下：



#include<iostream>
using namespace std;
class SuperOne
{
public:
         SuperOne();//默认构造函数
         SuperOne(intpubSuperOne,int proSuperOne,int priSuperOne);//含参数的构造函数,
         SuperOne(SuperOne & source);//拷贝构造函数
         SuperOne&operator=(SuperOne & source);//拷贝赋值运算符
         ~SuperOne();//析构函数
         int getPubSuperOne();
         int getProSuperOne();
         int getPriSuperOne();
         void setPubSuperOne(int pubSuperOne);
         void setProSuperOne(int proSuperOne);
         void setPriSuperOne(int priSuperOne);
         void PublicSuperOne();
         void Print();
protected:
       void    ProtectedSuperOne();
private:
         void   PrivateSuperOne();
         //Members
public:
         int    pubSuperOne;
protected:
         int    proSuperOne;
private:
         int     priSuperOne;
};
 
SuperOne::SuperOne()
{
         this->pubSuperOne= 0;
         this->proSuperOne= 0;
         this->priSuperOne= 0;
         cout<<"Defaultstructure function is called!"<<endl;
}
 
SuperOne::SuperOne(intpubSuperOne,int proSuperOne,int priSuperOne)
{
         this->pubSuperOne= pubSuperOne;
         this->proSuperOne= proSuperOne;
         this->priSuperOne= priSuperOne;
         cout<<"Structurefunction with three parameters is called!"<<endl;
}
 
SuperOne::SuperOne(SuperOne &source)
{
         this->pubSuperOne= source.pubSuperOne;
         this->proSuperOne= source.getProSuperOne();
         this->priSuperOne= source.getPriSuperOne();
         cout<<"Copystructure function is called!"<<endl;
}
 
SuperOne& SuperOne::operator=(SuperOne & source)
{
         this->pubSuperOne= source.pubSuperOne;
         this->proSuperOne= source.getProSuperOne();
         this->priSuperOne= source.getPriSuperOne();
         cout<<"Copystructure operator is called!"<<endl;
        
         return* this;
}
 
SuperOne::~SuperOne()
{
         cout<<"UnStructurefunction is called!"<<endl;
}
 
void SuperOne::Print()
{
         cout<<"SuperOnedata:\t";
         cout<<this->pubSuperOne<<""<<this->proSuperOne<<""<<this->priSuperOne<<endl;
}
int SuperOne::getPubSuperOne()
{
         returnthis->pubSuperOne;
}
 
void SuperOne::setPubSuperOne(intpubSuperOne)
{
         this->pubSuperOne= pubSuperOne;
}
 
int SuperOne::getProSuperOne()
{
         returnthis->proSuperOne;
}
 
void SuperOne::setProSuperOne(intproSuperOne)
{
         this->proSuperOne= proSuperOne;
}
 
int SuperOne::getPriSuperOne()
{
         returnthis->priSuperOne;
}
 
void SuperOne::setPriSuperOne(intpriSuperOne)
{
   this->priSuperOne = priSuperOne;
}
 
void SuperOne::PublicSuperOne()
{
         cout<<"PublicSuperOne is called!"<<endl;
}
 
void SuperOne::ProtectedSuperOne()
{
         cout<<"ProtectedSuperOne is called!"<<endl;
}
 
void SuperOne::PrivateSuperOne()
{
         cout<<"PrivateSuperOne is called!"<<endl;
}
 


int main()
{
	cout<<"1:\t";
	SuperOne s0;


	cout<<"2:\t";
	SuperOne s1(1,1,1);


	cout<<"3:\t";
	SuperOne s2(s0);


	cout<<"4:\t";
	SuperOne s3 = s1;
  
	cout<<"5:\t";
	s0.Print();


	cout<<"6:\t";
	s1.Print();


    cout<<"7:\t";
	s2.Print();


	cout<<"8:\t";
	s3.Print();


	cout<<"9:\t";
	s1=s0;


	cout<<"10:\t";
	s1.Print();


	cout<<"11:\t";
       SuperOne * s4 = new SuperOne();


	cout<<"12:\t";
	delete s4;


	cout<<"13:\t";
	SuperOne * s5 = new SuperOne(1,2,3);


	cout<<"14:\t";
	delete s5;


	return 1;
}

代码讲解：

1，默认构造函数

声明：类名();比如本例中的SuperOne();注意：没有返回值类型哦

用法: (1),在声明一个对象时被调用，比如1，SuperOne s0;这个时候默认的构造函数被调用，输出窗口的第 1 行就是。

(2),在使用new 运算符构造对象时使用，

比如20，SuperOne *s4 = new SuperOne();

输出窗口中第11行就是。

2, 带参数的构造函数

声明：类名(参数列表);本例中的SuperOne(intpubSuperOne,int proSuperOne,int priSuperOne);//构造函数就是，

用法：(1),用来对类中的数进行初始化，比如4 ,SuperOne s1(1,1,1)

在初始化的时候使用this->指针，比如更好的初始化方法是用下面的风格；

SuperOne::SuperOne(intpub,int pro,int pri)