What is the difference between the four transformations of const_cast,dynamic_cast,reinterpret_cast,static_ castings

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C++ is a strongly typed language, and the type checking is very strict. We can use the (NewType) Expression in C language to override the return value of a variable or expression, or we can use the new conversion operator provided in C++: const_cast,dynamic_cast,reinterpret_cast,static_cast. Here are four different scenarios used by transformations.

One, const_cast

As the name implies, const_cast is used to remove the constancy of an object so that Chang Liang can be modified. The type in const_cast (varible) must be a pointer, reference, or pointer to a member of the object type. For example, the following usage is wrong:

Change int to int& to compile normally, and the output a value is 4:

Three classes are defined. There are different member functions TestB () and TestC () in parent class A, subclass B and C, respectively, and then use A pointer to point to the A _ Magi B ~ C object from new and put it into an array:

At this point, the values of str and p are exactly the same, and the purpose of reinterpret_cast is to interpret the value of the pointer str as an integer in a binary way.

This kind of operation, which I have never used in practical projects, is limited to the understanding of written basic knowledge.

Four, static_cast

Static_cast is used to deal with implicit conversion, which is equivalent to (NewType) Expression overturn in C language. it can turn int into float, char* into int, the pointer to the base class into a pointer to a subclass, and non-const into a const object, but it cannot convert a const object into non-const (this is the function of const_cast).

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