为什么可以在类中声明静态常量成员，但不能在常量成员中声明呢? [英] Why is it possible to declare static constant member in a class but not constant member?

问题描述

为什么可以在一个类中声明一个静态常量成员，而不是一个常量成员?

hi why is it possible to declare a static constant member in a class but not a constant member?

推荐答案

它绝对是 可以在C ++类中声明和使用非静态常量成员.
请参见此 [

It is definitely possible to declare and use a non-static constant member in C++ classes.
See this[^] form Bjarne Stroustrup''s C++ Style and Technique FAQ. :)

您的意思是在类中初始化变量吗?

static const是一个变量，不会为该类的所有实例更改其值.

另一方面，const变量的值对于该类的一个实例不变，但对于不同的实例可以不同.

静态const示例-

Do you mean initialize the variable in-class ?

A static const is a variable that is not going to change its value for all instances of the class.

A const variable on the other hand can have a value that doesn''t change for one instance of the class, but can be different for different instances.

A static const example -

class A
{
public:
    static const int var = 100;
};

一个const示例-

A const example -

class A
{
public:
    const int var;

    A(int a) : var(a) {}
};

int main()
{
    A a(10);
    A b(20);
}

我想看
就像优化内存使用量一样::-D

I want to see it
just as an optimization of the memory usage... :-D

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