C++中ｃｏｎｓｔ的详细解释

原文网址：http://stackoverflow.com/questions/1143262/what-is-the-difference-between-const-int-const-int-const-int-const

Read it backwards...

• int* - pointer to int
• int const * - pointer to const int
• int * const - const pointer to int
• int const * const - const pointer to const int

Now the first const can be on either side of the type so:

• const int * == int const *
• const int * const == int const * const

If you want to go really crazy you can do things like this:

• int ** - pointer to pointer to int
• int ** const - a const pointer to a pointer to an int
• int * const * - a pointer to a const pointer to an int
• int const ** - a pointer to a pointer to a const int
• int * const * const - a const pointer to a const pointer to an int
• ...

And to make sure we are clear on the meaning of const

const int* foo;int *const bar; //note, you actually need to set the pointer                 //here because you can't change it later ;)

foo is a variable pointer to a constant int. That is you change what you point to but not the value that you point to. Most often this is seen with cstrings where you have a pointer to a const char. You may change which string you point to but you can't changed the strings content. This is important when the string itself is in the data segment of a program and shouldn't be changed.

bar is a const or fixed pointer to a value that can be changed. This is like a reference with out the extra syntactic sugar. Because of this fact, usually you would use a reference where you would use a T* const pointer unless you need to allow null pointers.

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typedef char *ASTRING;const ASTRING astring;

The type of astring is char * const, not const char *. This is one reason I always tend to put const to the right of the type, and never at the start.

更详细版本：http://www.parashift.com/c++-faq-lite/overview-const.html－－－C++ const百科全书。。

http://duramecho.com/ComputerInformation/WhyHowCppConst.html，const详解

http://www.cprogramming.com/tutorial/const_correctness.html，专家博客解释ｃｏｎｓｔ