c++ - 不能通过括号定义和初始化类成员

Question

This question already has an answer here:

Why class data members can't be initialized by direct initialization syntax?

(1个答案)


上个月关闭。

#include <iostream>
using namespace std;

class A
{
    public:
        A(): i(10) {}
        int i(5);   // error
//      int i = 5;     ok
//      int i = {5};   ok
//      int i{5};      ok
};

int main()
{
    int j(3); // ok
   return 0;
}

为什么不能使用括号在类中声明的成员处初始化成员，而可以使用其他形式？

最佳答案

完全不允许在类的成员规范中使用直接非列表初始化语法:

member-declarator-list - similar to a init-declarator-list, but additionally allows bit-field declaration, pure-specifier, and virt-specifier (override or final) (since C++11), and does not allow direct-non-list-initialization syntax.

https://en.cppreference.com/w/cpp/language/class#Member_specification

关于c++ - 不能通过括号定义和初始化类成员，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/64681958/

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Answer 1

完全不允许在类的成员规范中使用直接非列表初始化语法:

member-declarator-list - similar to a init-declarator-list, but additionally allows bit-field declaration, pure-specifier, and virt-specifier (override or final) (since C++11), and does not allow direct-non-list-initialization syntax.

https://en.cppreference.com/w/cpp/language/class#Member_specification