记录一些C++不常用功能点和一些C++的坑点,备查
Q.C++ using 关键字应用:
private 继承时,使用using 关键字在继承类中修改基类public成员的默认访问类型;
栗子:
class Base
{
public :
int baseMethod()
{
std::cout << "hi~";
return base_memeber;
}
int base_memeber = ;
private : };
class Inherit : private Base
{
public:
using Base::base_memeber;
using Base::baseMethod;
private:
};
Q.C++ static 关键字应用:
函数中可以使用 static 关键字 定义静态变量,其作用范围只在其函数体中有效.
栗子:
int baseMethod()
{
static int t = ;//只会初始化一次
t++;
std::cout << "hi t: " << t;
return t;
}
Q. C++ Template ... 与Decltype ():
#include <iostream>
#include "string" using namespace std; template<typename T>
void func_one(T& val)
{
cout << val << endl << "finished";
} //不可用
template< typename T, typename... Args>
auto func_two(int index, T& val, const Args&... args) -> decltype(T)
{
static int curIndex = ;
if (curIndex == index)
{
return val;
}
else
{
return func_two<T,Args...>(index, args...);
} } template<typename T,typename... Args>
void func_one(T& val, const Args&... args)
{
cout << val << endl;
cout << "Test:" << endl;
func_test(args...);
//func_one(args...);
} void func_test(double d, int i, string str)
{
cout << d << endl << i << endl << str << endl;
} int main()
{
int x; func_one("",2.0f,,""); cin>>x; return ;
}