STL::for_each

最新推荐文章于 2025-05-18 08:30:00 发布

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本文通过两个示例介绍了STL中for_each函数的应用。第一个示例展示了如何使用for_each遍历继承体系中的对象并调用虚函数。第二个示例则演示了如何使用for_each结合bind2nd来调用类成员函数。

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关于STL的for_each的使用，例子1：

class T1
{
public:
	virtual void S1()=0;
	virtual void S2()=0;
};

class T2 : public T1
{
public:
	virtual void S1() {
		printf("T2:S1\n");
	}
	virtual void S2() {
		printf("T2:S2\n");
	}
};

class T3_1 : public T2
{
public:
	virtual void S1() {
		printf("T3_1:S1\n");
	}
};

class T3_2 : public T2
{
public:
	virtual void S1() {
		printf("T3_2:S1\n");
	}
	virtual void S2() {
		printf("T3_2:S2\n");
	}
};


int _tmain(int argc, _TCHAR* argv[])
{

	typedef list<T1 *> TSTTB;
	TSTTB list1;
	list1.push_back(new T2());
	list1.push_back(new T3_1());
	list1.push_back(new T3_2());

	printf("T2-T3_1-T3_2\n===============================================\n");
	printf("调用&T1::S1\n===============================================\n");
	for_each(list1.begin(), list1.end(), mem_fun(&T1::S1));
	printf("调用&T1::S2\n===============================================\n");
	for_each(list1.begin(), list1.end(), mem_fun(&T1::S2));

	return 0;
}

下面是例子2：

int x = 0;
class TestBase
{
public:
	~TestBase() {
		printf("Name:%d release\n", m_x);
	}
	TestBase() {
		m_x = ++x;
	}
	virtual void ShowString(char *pChar) {
		printf("Name:%d, String: %s\n", m_x, pChar);
	}
	virtual void ShowString(int num) {
		printf("Name:%d, Num: %d\n", m_x, num);
	}
	virtual void ShowString() {
		printf("Name:%d\n", m_x);
	}
	virtual void ShowClass() {
		printf("TestBase\n");
	}
	
private:
	int m_x;
};

int _tmain(int argc, _TCHAR* argv[])
{
	typedef list<TestBase *> TSTTB;

	TSTTB t;
	t.push_back(new TestBase());
	t.push_back(new TestBase());
	t.push_back(new TestBase());
	t.push_back(new TestBase());

	for_each(t.begin(), t.end(), 
	       bind2nd(mem_fun1<void, TestBase, int>(&TestBase::ShowString), 1));  


	while (t.size()) {
		TestBase *p = t.front();
		t.pop_front();
		delete p;
	}

	return 0;
}