深入理解各种构造函数

#include<string.h>
#include<iostream>
using namespace std;

class test{
public:
    test(char *p ){

        cout << "this is construction of test"<< p << endl;

        if(p){
            pData = new char[strlen(p)+1];
            strcpy(pData, p );
        }
        else
        {
            pData = new char[1];
            *pData = '\0';

        }
    }
    test(const test & T){

        cout <<" this is copy construction of test " << T.pData<< endl;

        if(T.pData){
            pData = new char [strlen(T.pData)+1];
            strcpy( pData , T.pData);
        }
        else
        {
            pData = new char [1] ;
            *pData = '\0';
        }
    }
	
    test &operator = (const test & T){
		
        cout << "this is operator = :" << pData <<"=" << T.pData << endl ;
		
        if(this == &T)
            return *this;
		
        if(T.pData)
        {
            if(pData){
                delete [] pData;
            }
            pData = new char [strlen(T.pData) + 1];
            strcpy(pData , T.pData);
        }
        else
        {
            pData = new char[1];
            *pData = '\0';
        }
        return * this;
    }
	
    ~test(){
		
        cout << "this is dectruction of test "<< pData << endl ;
		
        delete [] pData;
    }
	void set( char*value)
	{
		if(value)
		{
			delete [] pData;
			pData = new char [strlen(value) + 1];
			strcpy(pData , value);
		}
	else
	{
		pData = new char[1];
		*pData = '\0';
        }

	}
	
private:
    char * pData;
};


 test fun( test Aa){  
        test Bb("    0000") ;  
        Bb = Aa ;
		Bb.set("    2222");
        return Bb ;  
    }  
  
  
  
 int main()
 {  
	 test A("    1111");  
	 test B = fun( A ) ;  
	 
	 test C = A ;  
	 A = B;
	 
 }  

运行结果如下：

this is construction of test 1111 //A的构造函数
this is copy construction of test 1111 //传值产生的结果，即A拷贝了一个Aa
this is construction of test 0000 //Bb的构造函数
this is operator = : 0000= 1111 //Bb=Aa的结果
this is copy construction of test 2222 //return Bb；用Bb构造了一个B，所以调用的是拷贝构造函数
this is dectruction of test 2222 //Bb的析构函数
this is dectruction of test 1111 //Aa的析构函数
this is copy construction of test 1111 //语句Test C = A 的构造函数，这里没有调用operator=，因为拷贝构造函数效率更高，算是一种优化把
this is operator = : 1111= 2222 //A=B操作的结果
this is dectruction of test 1111 //C的析构函数
this is dectruction of test 2222 //B的析构函数
this is dectruction of test 2222 //A的析构函数
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俗话说得好，好记性不如烂笔头啊，自己写得代码，现在居然看不懂了……