Here what we are trying to learn is the difference between:-
const char *;
and
char * const;
The difference is that const char * is a pointer to a const char, while char * const is a constant pointer to a char.
const char * :- In this, the value being pointed to can’t be changed but the pointer can be.
char * const :- In this, the value being pointed at can change but the pointer can’t.
The third type is
const char * const;
which is a constant pointer to a constant char (so nothing about it can be changed).
One rule of the thumb to remember this is by reading backwards:-
- char * const :- constant pointer to a character
- const char * :- pointer to a constant character
- const char * const:- constant pointer to a constant character
It will be more clear by this following example:-
#include<stdio.h>
int main()
{
const char * p; // value cannot be changed
char z;
//*p = 'c'; // this will not work
p = &z;
printf(" %c\n",*p);
return 0;
}
int main()
{
char * const p; // address cannot be changed
char z;
*p = 'c';
//p = &z; // this will not work
printf(" %c\n",*p);
return 0;
}
int main()
{
const char * const p; // both address and value cannot be changed
char z;
*p = 'c'; // this will not work
p = &z; // this will not work
printf(" %c\n",*p);
return 0;
}