C++11-14 第6讲 explicit关键字

explicit 用来针对构造函数有多个实参。

#include<iostream>
#include<initializer_list>
#include<array>
using namespace std;


struct Complex {//c++1.0版本
	int real, imag;
	explicit Complex(int re,int im=0):real(re),imag(im){}//禁止隐式转换，C++1.0就有
	Complex operator+(const Complex&x) {
		return Complex((real + x.real), (imag + x.imag));
	}
};

class P {
public:
	P(int a, int b) { cout << "P(int a,int b)" << endl; }
	P(initializer_list<int>){cout<<"P(initializer_list<int>)" << endl;}
	explicit P(int a, int b, int c) { cout << "explicit P(int a,int b,int c)"; }//c++11可以explicit几个的隐式转换
};
void fp(const &P){}
int main() {
	Complex a(12,5);
	//Complex b = a + 5;
	P p1(77, 5);
	P p2{ 77,5 };
	P p3{ 77,5,1 };
	P p4 = { 77,5 };
	P p5 = { 1,2,3 };
	P p11{ 1,2,3,4 };


	system("pause");
	return 0;
}