c++ type trait 之 类型修饰符(Type Modifier)改动类型

#include <iostream>using namespace std;int main(){    int a = 5;    add_const<int *>::type b = &a;//int * const    //关于引用遵守引用折叠规则    add_lvalue_reference<int&&>::type c = a;// int &    add_rvalue_reference<int&>::type d = a; // int &    add_pointer<int>::type e = &a; //int*    //传入reference会导致不明确行为    make_signed<unsigned>::type f = -5; // int    make_unsigned<int>::type g = 5;//unsigned    //去除row const    remove_const<decltype(b)>::type m = &a;// int*    remove_reference<int&&>::type n = 5;//int    remove_pointer<int*>::type j = 6;//int    //去除row volatile    remove_volatile<int *volatile>::type i = &a; //int*    remove_cv<const int *volatile>::type k = &a; // const int*    add_volatile<int>::type w = 4;// volatile int    add_cv<int*>::type v = &a; // int*volatile const    system("pause");    return 0;}