C ++ value of using const in signature

Question

Please help me understand the following signature:

err_type funcName(const Type& buffer) const;

so for the first const does this mean that the contents of the Type cannot change or that the link cannot change?

secondly, what does the second constant mean? I don’t even have a hint.

Thanks in advance, JBU

Answer 1

The second constant means that the method can be called for the const object.

Consider the following example:

class foo
{
public:
    void const_method() const;
    void nonconst_method();
};

void doit()
{
    const foo f;

    f.const_method();      // this is okay
    f.nonconst_method();   // the compiler will not allow this
}

In addition, the const method does not allow changes to any elements of the object (unless the element is marked as mutable):

class foo
{
public:
    void const_method() const;

private:
    int r;
    mutable int m;
};

void foo::const_method() const
{
    m = 0; // this is okay as m is marked mutable
    r = 0; // the compiler will not allow this
}

Answer 2

Yes, the first constmeans that bufferit cannot change.

const , - (this).

Answer 3

, , , :  http://www.parashift.com/c++-faq-lite/const-correctness.html

Answer 4

: , , ​​ . .

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, "<method> const". ( - , .)

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• int const* id & emsp; = int
• int* const id & emsp; = int
• int const id[5] & emsp; = 5x int
• int (*const id)[5] & emsp; = 5x int

T const& T const* , , . , , .

Answer 5

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Answer 6

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Answer 7

, , , - mutable. mutable - , , const. , memoizing , .