C++中虚函数重写及普通函数重写

C++中虚函数重写，那么会出现多态的现象，普通方法重写不会出现多态的现象。

虚函数重写，那么如果以父类身份出现，始终调用的都是实际子类的方法，普通方法却不是。

具体为什么会有多态现象请参考 ：http://sinfrancis.iteye.com/admin/blogs/484374

 

这里使用了三个类做实验，分别是Base1、Base3、Child2 ，Base3继承Base1，Child继承Base3，

Base1中含有一个普通方法和一个虚函数，并且Base3和Child2中都重写了这些方法代码如下：

 

Base1.h

/*
 * Base1.h
 *
 *  Created on: 2009-12-3
 *      Author: Administrator
 */

#ifndef BASE1_H_
#define BASE1_H_

class Base1 {
public:
	Base1();
	virtual ~Base1();
	virtual int testVirtual();
	int testCommon();

};

#endif /* BASE1_H_ */

 

 

 

Base1.cpp

/*
 * Base1.cpp
 *
 *  Created on: 2009-12-3
 *      Author: Administrator
 */

#include "Base1.h"
#include <iostream>
using namespace std;
Base1::Base1() {
	// TODO Auto-generated constructor stub

}

Base1::~Base1() {
	// TODO Auto-generated destructor stub
}
 int Base1::testVirtual() {
	cout << "Base1::testVirtual()" << endl;
	return 1;
}

 int Base1::testCommon(){
	 cout << "Base1::testCommon()" << endl;
	 return 1;
 }

 

 

 

Base3.h

/*
 * Base3.h
 *
 *  Created on: 2009-12-3
 *      Author: Administrator
 */

#ifndef BASE3_H_
#define BASE3_H_
#include "Base1.h"
class Base3 :public Base1{
public:
	Base3();
	virtual ~Base3();
	virtual int testVirtual();
	int testCommon();
};

#endif /* BASE3_H_ */

 

 

 

Base3.cpp

/*
 * Base3.cpp
 *
 *  Created on: 2009-12-3
 *      Author: Administrator
 */

#include "Base3.h"
#include  <iostream>
using namespace std;
Base3::Base3() {
	// TODO Auto-generated constructor stub
}

Base3::~Base3() {
	// TODO Auto-generated destructor stub
}

int Base3::testVirtual(){
	cout << "Base3::testVirtual()" << endl;
	return 1;
}
int Base3::testCommon(){
	 cout << "Base3::testCommon()" << endl;
	 return 1;
}

 

 

Child2.h

 

/*
 * Child2.h
 *
 *  Created on: 2009-12-3
 *      Author: Administrator
 */

#ifndef CHILD2_H_
#define CHILD2_H_

#include "Base1.h"
#include "Base3.h"
class Child2:public Base3{
public:
	Child2();
	virtual ~Child2();
	virtual int testVirtual();
	int testCommon();
};

#endif /* CHILD2_H_ */

 

 

Child2.cpp

/*
 * Child2.cpp
 *
 *  Created on: 2009-12-3
 *      Author: Administrator
 */

#include "Child2.h"
#include <iostream>
using namespace std;
Child2::Child2() {
	// TODO Auto-generated constructor stub
}

Child2::~Child2() {
	// TODO Auto-generated destructor stub
}


int Child2::testVirtual(){
	cout << "Child2::testVirtual()" << endl;
	return 0;
}
int Child2::testCommon(){
	cout << "Child2::testCommon()" << endl;
		return 0;
}

 

 

 

test.cpp

 

#include "Base3.h"
#include "Base1.h"
#include "Child2.h"
#include <iostream>
using namespace std;
int main(int argc, char **argv) {
	Base3 b3;
	cout << sizeof(b3) << endl;
	b3.testVirtual();

	Base3 *b1 = new Child2();

	b1->testVirtual();
	b1->testCommon();

	Base1 *b2 = new Child2();
	b2->testVirtual();
	b2->testCommon();

	Child2 *c2 = new Child2();
	c2->testVirtual();
	c2->testCommon();

	delete (b1);
	delete (b2);
	delete (c2);

}

 

 

 

运行结果：

 

4
Base3::testVirtual()
Child2::testVirtual()
Base3::testCommon()
Child2::testVirtual()
Base1::testCommon()
Child2::testVirtual()
Child2::testCommon()