Int * P, cons int * P, int const * P, int * const P, const int * const P, int const * const P

Zookeeper

1. Analysis of several cases with the const keyword

Const modified code	Meaning (features)	Equivalence
Int * P = & num;	1. You can read yourself 2. You can change yourself through * P. 3. You can view other users through P = & Data	Maximum Permissions
Cons int * P = & num;	1. Putting const on the left means that it points to a constant, which cannot be modified, 2. p = & data; (the address can be modified) 3. * P = 30; (this time is incorrect)	The two are equivalent (Application: View others' accounts)
Int const * P = & num;	(Equivalent to the above) the limit can only be read, cannot be modified, and the address can be moved
Int * const P = & num;	You cannot modify your own address, but you can use * P to modify your own value.
Const int * const P = & num;	You cannot modify the address to view other values or modify your own values. You can only view your own values.	1. You can view yourself 2. Do not change yourself 3. Do not look at others
Int const * const P = & num;	Only your account can be read and not written.

 

1. Values can only be assigned during initialization (const limits that variables cannot be modified randomly)

2. Const Summary

On the left side of '*', const indicates that I am pointing to a constant.

On the right side of '*', const indicates a constant of the pointer.

You cannot change the above P = & data; to * P = 3. As follows:

 

1. Int const * P

1. Int * const P; you cannot modify your own address, but you can use * P to modify your own value.

You can modify it in * P mode.

6. Const int * const P = & data; in this way, you can only view your own data, neither modify others nor change yourself.

You can only view yourself: