成员字段，构建顺序

2022-01-18 00:00:00 initialization c++

在 C++ 中，当执行如下所示的操作时，构造顺序是否得到保证?

In C++, when doing something like what you see below, is the order of construction guaranteed?

Logger::Logger()
    : kFilePath_("../logs/runtime.log"), logFile_(kFilePath_)
{
    // ...
}

推荐答案

是的，总是保证构造的顺序.但是，它不能保证与对象在初始化列表中出现的顺序相同.

Yes, the order of construction is always guaranteed. It is not, however, guaranteed to be the same as the order in which the objects appear in the initializer list.

成员变量是按照它们在类主体中声明的顺序构造的.例如:

Member variables are constructed in the order in which they are declared in the body of the class. For example:

struct A { };
struct B { };

struct S {
    A a;
    B b;

    S() : b(), a() { }
};

首先构造

a，然后构造b.成员变量出现在初始化列表中的顺序无关紧要.

a is constructed first, then b. The order in which member variables appear in the initializer list is irrelevant.

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