Attempting to modify data through a non-constant pointer to constant data. : const pointer « Pointer « C Tutorial

1. C Tutorial
2. Pointer
3. const pointer

xPtr cannot be used to modify the value of the variable to which it points.

#include <stdio.h>

void f( const int *xPtr );

int main()
{
   int y;       

   f( &y );     

   return 0;    
}

void f( const int *xPtr )
{
   //*xPtr = 100;  /* error: cannot modify a const object */
}