C-type delimiters const and volatile

C-type delimiters const and volatile 1. Const In the Declaration, const usually appears after the storage type and before the data type. For example: Static const int A = 3; // A is an integer constant of the static storage type. Since the const has been used to limit the type of A, we can initialize a, but we cannot assign values to a, increment and reduce operations in the future. Although const is used to restrict variables, it is not allowed to describe the size of the array with variables in another declaration. Error Example 1: Const int K = 3; Int array [k]; // Error Therefore, variables restricted by const are not equivalent to symbolic constants. Error Example 2: The address of the Variable Limited by const is assigned to an unlimited pointer. Const int A = 7; Int * P = & A; // Error Cause of error: P is a common pointer to an int. Then we can use it in an expression like ++ * P, but it will change the value of, this is contrary to the probability of a constant.
Example 2: Const int A = 7; Const int * P = & A; // P is a pointer to an int-type constant. Its initial value is the address of.  
Note: P itself is not a constant. We can assign values to it using some other addresses, but we cannot assign values to * P. We should not modify the object pointed to by P.
If we want to make P itself a constant rather than a, we can declare it as follows: Int; Int * const P = & A; // P is a constant pointer to an int. After that, we cannot assign values to P, but can assign values to * P.