我应该使用初始化程序列表还是在C构造函数中执行赋值？

发布时间：2020-12-16 03:18:44 所属栏目：百科来源：网络整理

导读：class Node{public: Node *parent; // used during the search to record the parent of successor nodes Node *child; // used after the search for the application to view the search in reverse float g; // cost of this node + it's predecessors fl

class Node
{
public:

    Node *parent; // used during the search to record the parent of successor nodes
    Node *child; // used after the search for the application to view the search in reverse

    float g; // cost of this node + it's predecessors
    float h; // heuristic estimate of distance to goal
    float f; // sum of cumulative cost of predecessors and self and heuristic

    Node() :
            parent( 0 ),child( 0 ),g( 0.0f ),h( 0.0f ),f( 0.0f )
    {
    }

    UserState m_UserState;
};

为什么我们应该使用构造函数

Node() :
            parent( 0 ),f( 0.0f )
    {
    }

代替

Node()
    {
        parent = null;
        child = null;
        g = 0.0f;
        h = 0.0f;
        f = 0.0f;
    }

谢谢：)

解决方法

对于简单的旧数据(POD),这没有什么好处,但一旦开始使用引用或组合类,它会有所不同：

class Foo {
    Bar bar;

  public:
    // construct bar from x
    Foo(int x) : bar(x) { }
};

与

Foo::Foo(int x)
{
    // bar is default-constructed; how do we "re-construct" it from x?
    bar = x;  // requires operator=(int) on bar; even if that's available,// time is wasted default-constructing bar
}

有时,一旦构造了对象,你甚至不会有一种“重新构建”对象的方式,因为类可能不支持setter或operator =. const成员肯定不能“重新构建”或重置：

class FooWithConstBar {
    const Bar bar;

  public:
    Foo(int x) {
        // bar is cast in stone for the lifetime of this Foo object
    }
};

编辑：感谢@Vitus指出引用的问题.

（编辑：李大同）

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