explicit 关键字声明 不能隐式调用构造函数

class Test1{public:Test1(int n) { num = n; } //普通构造函数private:int num;};class Test2{public:explicit Test2(int n) { num = n; } //explicit(显式)构造函数private:int num;};int main(){Test1 t1 = 12; //隐式调用其构造函数, 成功Test2 t2 = 12; //编译错误,不能隐式调用其构造函数Test2 t3(12); //显式调用成功return 0;}