What is the difference between char * const and const char *?

Question

What\'s the difference between:

char * const 

and

const char *

Answer 1

1. Constant pointer: A constant pointer can point only to a single variable of the respective data type during the entire program.we can change the value of the variable pointed by the pointer. Initialization should be done during the time of declaration itself.

Syntax:

datatype *const var;

char *const comes under this case.

/*program to illustrate the behaviour of constant pointer */

#include
int main(){
  int a=10;
  int *const ptr=&a;
  *ptr=100;/* we can change the value of object but we cannot point it to another variable.suppose another variable int b=20; and ptr=&b; gives you error*/
  printf("%d",*ptr);
  return 0;
}

2. Pointer to a const value: In this a pointer can point any number of variables of the respective type but we cannot change the value of the object pointed by the pointer at that specific time.

Syntax:

const datatype *varor datatype const *var

const char* comes under this case.

/* program to illustrate the behavior of pointer to a constant*/

   #include
   int main(){
       int a=10,b=20;
       int const *ptr=&a;
       printf("%d\n",*ptr);
       /*  *ptr=100 is not possible i.e we cannot change the value of the object pointed by the pointer*/
       ptr=&b;
       printf("%d",*ptr);
       /*we can point it to another object*/
       return 0;
    }