What is the difference between these declarations in C?

Question

In C and C++ what do the following declarations do?

const int * i;
int * const i;
const volatile int ip;
const int *i;

Are any of the above

Answer 1

You read variables declarations in C/C++ right-to-left, so to speak.

const int *i;  // pointer to a constant int (the integer value doesn't change)

int *const i;  // constant pointer to an int (what i points to doesn't change)

const volatile int ip;  // a constant integer whose value will never be cached by the system

They each have their own purposes. Any C++ textbook or half decent resource will have explanations of each.