C + + const and const_cast

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Today, we visited the quiz community,

In C + +, I saw someone asking about const_cast,

Just in the <<effective c++>>, also talked about this aspect of things.

Turned over the book, the Internet search,

Found it kinda fun ....

The main question is how to set a const double type array to re-release the const during run time, then change the contents of the array.

> First, make it clear,

For const_cast

This thing, just for pointers and references to the solution const, for variables, there will be problems.

For example, look at the following code:

const int a=789; int &b = Const_cast<int&> (a); int *c = const_cast<int*> (&a);cout<< "A=" <<a<<endl;cout<< "&b=" <<b<<endl;cout<< "*c=" <<*c<<endl;cout << "&a=" <<&a<<endl;cout << "&b=" <<&b<<endl;cout << "c=" <<c<<endl;cout<<endl;b = 987;*c = 999;cout << "a=" <<a<<endl;cout << "b=" < <b<<endl;cout << "*c=" <<*c<<endl;cout << "&a=" <<&a<<endl;cout << "&b=" <<&b<<endl;cout << "c=" <<c<<endl;

Run it:

It's fun. ~

> Then, for this question,

Because it is an array, the array belongs to the category of pointers,

I just tried to write,

Found

Through an intermediate variable, you can still change the contents of the original const:

Const double Arr[3] = {1.2,3.3,4.5};int i;for (i=0;i<3;++i) cout<<arr[i]<< ""; cout<<endl;double & temp = const_cast<double&> (arr[0]); for (i=0;i<3;++i) cout<<arr[i]<< "";cout<< endl;cout<<temp<<endl;cout<<arr[0]<<endl;cout<<&temp<<endl;cout< <&arr[0]<<endl;

The result is still possible.

OK, that's it,

Very interesting stuff ~. ~

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C + + const and const_cast