模板

template<typename T>
T add(const T&a, const T &b)
{
    return a+b;
}
void func(int(*ptrfun)(const int& a, const int& b)) //后面两个参数的声明必须写
{
    cout<<"int"<<endl;
}
void func(string(*ptrfun)(const string& a,const string& b))
{
    cout<<"string"<<endl;
    
}
void main()
{
    func(add<int>);
    
}

#include <iostream>

template<typename T0,
    typename T1,
    typename T2,
    typename T3,
    typename T4>
    T2 func(T1 v1, T3 v3, T4 v4);

int main() {

    double sv2;

    using namespace std;
    sv2 = func<double, int, int>(1, 2, 3);
    cout << "	sv2: " << sv2 << endl;

    sv2 = func<double, int, int>(1, 2, 3);
    cout << "	sv2: " << sv2 << endl;

    sv2 = func<double, int, int>(1, 0.1, 0.1);
    cout << "	sv2: " << sv2 << endl;

    sv2 = func<int, double, double>(0.1, 0.1, 0.1);
    cout << "	sv2: " << sv2 << endl;
}

template<typename T0,
    typename T1,
    typename T2,
    typename T3,
    typename T4>
    T2 func(T1 v1, T3 v3, T4 v4)
{
    T0 static sv0 = T0(0);
    T2 static sv2 = T2(0);

    std::cout << "	v1: " << v1
        << "	v3: " << v3
        << "	v4: " << v4
        << "	|| sv0: " << sv0;

    T2 v2 = sv2;

    sv0 -= 1;
    sv2 -= 1;

    return v2;
}

// 文件名caller1.cpp
 #include <iostream>
 
template<typename T>
 void func(T const &v)
 {
     std::cout << "func1: " << v << std::endl;
 }
 
void caller1() {
     func(1);
     func(0.1);
 }
 
// ======================================
 // 文件名caller2.cpp
 #include <iostream>
 
template<typename T>
 void func(T const &v)
 {
     std::cout << "func2: " << v << std::endl;
 }
 
void caller2() {
     func(2);
     func(0.2f);
 }
 
// ======================================
 // 文件名main.cpp
 void caller1();
 void caller2();
 
int main()
 {
     caller1();
     caller2();
     return 0;
 }

template<typename T>
T add(const T&a, const T &b)
{
    return a+b;
}
void func(int(*ptrfun)(const int& a, const int& b),const int& a, const int&b) //后面两个参数的声明必须写
{
    ptrfun=add<int>;
    cout<<ptrfun(a,b)<<endl;
}
void func(string(*ptrfun)(const string& a,const string& b),const string& a,const string& b)
{
    ptrfun=add<string>;
    cout<<ptrfun(a,b)<<endl;
}
void main()
{
    func(add,1,2);
    func(add,"hello","world");
}

template<typename T>
T add(const T&a, const T &b)
{
    return a+b;
}
void func(int(*ptrfun)(const int& a, const int& b)) //后面两个参数的声明必须写
{
    cout<<"int"<<endl;
}
void func(string(*ptrfun)(const string& a,const string& b))
{
    cout<<"string"<<endl;
    
}
void main()
{
    func(add<int>);
    
}

template<typename T> class my_stack; // 前置栈类模板声明

template<typename T>
class list_node
{
    T value;
    list_node *next;

    // 私有构造函数，只能由其友类构造
    list_node(T const &v, list_node *n) :value(v), next(n) {}

    // 友类必须是类模板my_stack的实例
    friend class my_stack<T>;
};

template<typename T=int>
class my_stack
{
private:
    typedef list_node<T> node_type;//<T>不可省略
    node_type *head;

    // my_stack不可复制构造，也不可赋值
    my_stack operator=(my_stack const &) {}
    my_stack(my_stack const &s) {}

public:
    // 构造与析构
    my_stack() : head(0) {}
    ~my_stack() {while (!empty()) pop();}


    // 在类模板内实现的成员函数模板
    bool empty() const {return head == 0;}
    T const& top() const 
    {
        if (empty())
            throw std::runtime_error("stack is empty.");
        return head->value;
    }
    void push(T const &v) {head = new node_type(v, head);}

    // 成员函数声明，将在类模板外实现
    void pop();
};

// 在类模板外实现的成员函数模板
template<typename T>
void my_stack<T>::pop()
{
    if (head) {
        node_type *tmp = head;
        head = head->next;
        delete tmp;
    }
}


//子类模板：计数栈
template<typename T=int>
class count_stack : public my_stack<T>
{
    typedef my_stack<T> base_type; // 非常有用的typedef
    unsigned size;
public:
    count_stack() : base_type(), size(0) {}

    void push(T const &v) {
        base_type::push(v);
        size++;
    }

    void pop() {
        if (size > 0) {
            base_type::pop();
            size--;
        }
    }

    unsigned getSize() const {return size;}
};

#include "stack.h"


int main()
{
    my_stack<> mystack;
    mystack.push(2);
    cout<<mystack.top()<<endl;

    count_stack<> costack;
    costack.push(9);
    costack.push(8);
    costack.push(7);
    cout<<costack.getSize()<<endl;

    return 0;
}

struct normal_class
{
    int value;
    template<typename T>
    void set(T const &v) {value = int(v);}
    template<typename T>
    T get();
};

template<typename T>
T normal_class::get()
{
    return T(value);
}

template<typename T0>
struct a_class_template
{
    T0 value;

    template<typename T1>
    void set(T1 const &v){value = T0(v);}

    template<typename T1>
    T1 get();
};

// 类模板的成员函数模板在类模板外的实现方法
template<typename T0> template<typename T1>
T1 a_class_template<T0>::get()
{
    return T1(value);
}

template<typename T> 
class the_class  
{   
public:
	static int id;      
	the_class() {++id;} 
	static T getid(){return T(id)/2;}
};   
template<typename T> int the_class<T>::id = 1; 

　　

#include "the_class.h"   
void call()  
{      
    the_class<int> c;      
    std::cout << c.id << std::endl;  
}  

#include "the_class.h"  
void call1()  
{      
    the_class<int> c;      
    std::cout << c.id << std::endl;  
}  

void call(); 
void call1();   
int main()  
{     
    call();      
    call1();

}