深入分析C++模板特化与偏特化

#include <iostream>
using namespace std;

template<typename T> T Max(T t1,T t2)
{
return (t1>t2)?t1:t2;
}

typedef const char* CCP;
template<> CCP Max<CCP>(CCP s1,CCP s2)
{
return (strcmp(s1,s2)>0)?s1:s2;
}

int main()
{
//调用实例：int Max<int>(int,int)
int i=Max(10,5);
//调用显示特化：const char* Max<const char*>(const char*,const char*)
const char* p=Max<const char*>("very","good");
cout<<"i:"<<i<<endl;
cout<<"p:"<<p<<endl;
}

typedef const char* CCP;
CCP Max(CCP s1,CCP s2)
{
return (strcmp(s1,s2)>0)?s1:s2;
}

#include <iostream>
using namespace std;

template<typename T>class A
{
T num;
public:
A()
{
num=T(6.6);
}
void print()
{
cout<<"A'num:"<<num<<endl;
}
};

template<> class A<char*>
{
char* str;
public:
A(){
str="A' special definition ";
}
void print(){
cout<<str<<endl;
}
};

int main()
{
A<int> a1; //显示模板实参的隐式实例化
a1.print();
A<char*> a2; //使用特化的类模板
A2.print();
}

#include <vector>
#include <iostream> 
using namespace std;

//函数模板
template<typename T, class N> void compare(T num1, N num2)
{
cout << "standard function template" << endl;
if(num1>num2)
cout << "num1:" << num1 << " > num2:" << num2 <<endl;
else
cout << "num1:" << num1 << " <= num2:" << num2 << endl;
}

//对部分模板参数进行特化
template<class N> void compare(int num1, N num2)
{
cout<< "partitial specialization" <<endl;
if (num1>num2)
cout << "num1:" << num1 << " > num2:" << num2 << endl;
else
cout << "num1:" << num1 << " <= num2:" << num2 << endl;
}

//将模板参数特化为指针
template<typename T, class N> void compare(T* num1, N* num2)
{
cout << "new partitial specialization" << endl;
if (*num1>*num2)
cout << "num1:" << *num1 << " > num2:" << *num2 << endl;
else
cout << "num1:" << *num1 << " <= num2:" << *num2 << endl;
}

//将模板参数特化为另一个模板类
template<typename T, class N> void compare(std::vector<T>& vecLeft, std::vector<T>& vecRight)
{
cout << "to vector partitial specialization" << endl;
if (vecLeft.size()>vecRight.size())
cout << "vecLeft.size()" << vecLeft.size() << " > vecRight.size():" << vecRight.size() << endl;
else
cout << "vecLeft.size()" << vecLeft.size() << " <= vecRight.size():" << vecRight.size() << endl;
}

int main()
{
compare<int,int>(30,31);//调用非特化版本compare<int,int>(int num1, int num2)

compare(30,'1'); //调用偏特化版本compare<char>(int num1, char num2)

int a = 30;
char c = '1';
compare(&a,&c); //调用偏特化版本compare<int,char>(int* num1, char* num2)

vector<int> vecLeft{0};
vector<int> vecRight{1,2,3};
compare<int,int>(vecLeft,vecRight); //调用偏特化版本compare<int,char>(int* num1, char* num2)
}

#include <vector>
#include <iostream> 
using namespace std;

//类模板
template<typename T, class N> class TestClass
{
public:
static bool comp(T num1, N num2)
{
cout <<"standard class template"<< endl;
return (num1<num2) ? true : false;
}
};

//对部分模板参数进行特化
template<class N> class TestClass<int, N>
{
public:
static bool comp(int num1, N num2)
{
cout << "partitial specialization" << endl;
return (num1<num2) ? true : false;
}
};

//将模板参数特化为指针
template<typename T, class N> class TestClass<T*, N*>
{
public:
static bool comp(T* num1, N* num2)
{
cout << "new partitial specialization" << endl;
return (*num1<*num2) ? true : false;
}
};

//将模板参数特化为另一个模板类
template<typename T, class N> class TestClass<vector<T>,vector<N>>
{
public:
static bool comp(const vector<T>& vecLeft, const vector<N>& vecRight)
{
cout << "to vector partitial specialization" << endl;
return (vecLeft.size()<vecRight.size()) ? true : false;
}
};

int main()
{
//调用非特化版本
cout << TestClass<char, char>::comp('0', '1') << endl; 

//调用部分模板参数特化版本
cout << TestClass<int,char>::comp(30, '1') << endl; 

//调用模板参数特化为指针版本
int a = 30;
char c = '1';
cout << TestClass<int*, char*>::comp(&a, &c) << endl; 

//调用模板参数特化为另一个模板类版本
vector<int> vecLeft{0};
vector<int> vecRight{1,2,3};
cout << TestClass<vector<int>, vector<int>>::comp(vecLeft,vecRight) << endl; 
}