C ++初始化 [英] C++ initialization

问题描述

可能重复：

初始值的类构造

在 http://en.wikipedia.org/wiki/Delegation_pattern 中的c ++示例我注意到了我所避免的问题之前看过：

While I was looking at c++ example in http://en.wikipedia.org/wiki/Delegation_pattern I noticed something I haven't seen before:

C() : i(new A()) { }

我的问题是：这行代码与以下代码有什么不同：

My question is: How is this line of code any different from:

C() {
    i = new A();
}

：后的构造函数？ new A（）的括号是什么？

What does : after constructor do? What does the brackets around new A() do?

推荐答案

名为初始化列表。它用于初始化类的数据成员。

Its called initialization list. It is used to initialize the data members of a class.

C() {
    i = new A(); // i is not initialized here, here assignment is taking place.
}

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