C++ vector的delete与clear的区别 - 析构函数

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C++ vector的delete与clear的区别 - 析构函数

标签： C++ vector delete clear 析构函数分类： CPlusPlus 2011-04-14 22:52

1.clear() 不调用析构函数

2.delete *it 调用析构函数
可用以下程序测试出来：

#include <iostream>

#include <string>

#include <fstream>

#include <vector>

using namespace std;

ofstream txtout("test.txt");

class A

{

public:

A()

{ txtout<< "A constructor! "<<endl;

}

virtual~A();

};

A::~A()

{ txtout<< "A destructor! "<<endl;

}

const int test_size= 10;

int main()

{

{ vector< A* >the_vector,the_vector_copy;

A*pa;

for( inti=0;i <test_size;i++ )

{ pa = newA();

the_vector.push_back(pa);

the_vector_copy.push_back(pa);

}

txtout<<endl;

txtout<< "beforedelete... "<<endl;

pa= the_vector[0];

deletepa;

txtout<< "afterdelete... "<<endl;

txtout<<endl;

txtout<< "beforeclear... "<<endl;

the_vector.clear();

txtout<< "after clear..."<<endl;

txtout<<endl;

txtout<< "before alldeleting... "<<endl;

for( inti=1;i <test_size;i++ )

deletethe_vector_copy[i];

}

txtout<< "after all deleting... "<<endl;

txtout<<endl;

}

code::blocks 运行结果：

A constructor!

before delete...

A destructor!

after delete...

before clear...

after clear...

before all deleting...

A destructor!

after all deleting...