What is the difference between const int*, const int * const, and int const *?

Question

I always mess up how to use `const int*`, `const int * const`, and `int const *` correctly. Is there a set of rules defining what you can and cannot do? I want to know all the do's and all don'ts in terms of assignments, passing to the functions, etc.

Answer 1

The way i normally reminds people how they can interpret it is like follow these simple steps:

1. const keyword will be first applied to whatever we write on its left side
2. If there is nothing on its left side it will applied to whatever it is written on its right side

Back to your question:

const int* samplePtr;

/* samplePtr is a pointer to constant integer, this means you can update the

pointer but not its content */

const int* const samplePtr;

/*Here we have two constant, the most left one is same as previous example it

will be applied to int, but the right most one is applied to * this time.

In summary samplePtr is a constant pointer that points to a constant integer.

In other words, neither of the pointer and its content can be modified later*/

int const * samlePtr;

/* I did not this format very often but it is exactly same as first one

"const int * samplePtr" */

In summary i can say "const T" and "T const are identical"