Can i declare member variable as const in class of c++?if yes,how?

Question

我可以在C ++类中将成员变量声明为const吗？

Answer 1

You can - you put const in front of the type name.

class C
{
     const int x;

public:
      C() : x (5) { }
};

Answer 2

You declare it as you would if it wasn't a member. Note that declaring a variable as const will have considerable effects on the way that the class is used. You will definitely need a constructor to initialise it:

class A {
    public:
        A( int x ) : cvar( x ) {}
    private:
        const int cvar;
};

Answer 3

Sure, the simplest way is like this if the value will be the same across all instances of your class:

class X
{
public:
    static const int i = 1;
};

Or if you don't want it static:

class X
{
public:
    const int i;
    X(int the_i) : i(the_i)
    {     
    }
};