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This article mainly explains "what is the difference between C++ front + and post +". The content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought. Let's study and learn "what is the difference between C++ front + and post + +"!

Front + +:

Type operator++ ()

Post +:

Const type operator++ (int)

In order for the compiler to distinguish between pre-and post-+, C++ specifies that the suffix form has an int type parameter, and when the function is called, the compiler passes a value of 0 as the int parameter to the function. If it is not stipulated in this way, it cannot be distinguished, because they only take their own objects as input parameters.

Here is a simple example:

Class CInt {private: int masked value; / /}; CInt & CInt:: operator + + () / / is preceded by no parameters, and returns reference {this-> m_value + = 1; return * this;} const CInt CInt::peartor + + (Int) / / with an anonymous parameter and returns a value of {CInt old = * this; + + (* this); return old;}

The above implementation explains a key problem: front is more efficient than post, which needs to construct temporary objects and return.

So why are the pre-and post-return parameters different?

The prefix simply operates on itself and returns itself, so that the outside can directly operate on the returned object, such as

(+ + it)-> function ()

Because the postposition does not return the original object, the additional operation at this time will change the state of the temporary object, which is not different and is easy to be misunderstood.

So why not return const &? Because this cannot be done, the return reference will be invalid and the temporary object no longer exists.

So the post-return const object restricts mismanipulation of the temporary object and explicitly tells the caller that the object is only a copy of the original object.

There is another reason: the built-in int type does not support iTunes. If the post + + returns a modifiable copy, the behavior of the built-in int type will be different. Therefore, users should be prohibited from modifying the return value.

Thank you for your reading, the above is the content of "what is the difference between C++ front + and post +". After the study of this article, I believe you have a deeper understanding of what is the difference between C++ front + and post +, and the specific use still needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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