谁能解释一下C++中的模板究竟是怎么会回事

[星之瀚海]

谁能解释一下C++中的模板究竟是怎么会回事

[joachern]

和函数模板一样
比如
template <type T>
print( T a)
{
cout<<a<<endl;
};
因为cout支持任何数据类型的输出，所以可以避免些 print(int) print(long) print(double) 等函数了

看看下面的代码

//感受C++模板变成
#include <iostream>

template <class T, void (T::*SF)(), void (T::*EF)()>
class AutoRunner
{
public:
AutoRunner (T &instance) : m_instance(instance) { (m_instance.*SF)();}
~AutoRunner () { (m_instance.*EF)();}
private:
T &m_instance;
};

class MyClass
{
public:
MyClass (long value) : m_value(value) {}
void FirstMethod() { std::cout << " FirstMethod, value is " << m_value << std::endl;}
void LastMethod () { std::cout << " LastMethod , value is " << m_value << std::endl;}
private:
long m_value;
};

typedef AutoRunner<MyClass,&MyClass::FirstMethod,&MyClass::LastMethod> MyClassAuto;

int main()
{
std::cout << "In beginning of main" << std::endl;

MyClass myInstance(1);
MyClass myInstance2(2);
{
MyClassAuto myClassAuto(myInstance);
std::cout << " In sub block" << std::endl;
}
{
MyClassAuto myClassAuto(myInstance2);
std::cout << " In sub block" << std::endl;
}

std::cout << "At end of main" << std::endl;

return 0;
}