constants in C/C++ Post: 26695

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Top Forums Programming constants in C/C++ Post 26695 by Shobhit on Thursday 22nd of August 2002 09:23:50 AM

08-22-2002

Registered User

constants in C/C++

Hi all
My question is related to following sample code which tries to change consant value by pointers.(I know it is wrong practice but i am surprised by mis-behaviour)
The code:

#include <stdio.h>

int main()
{
const int x = 10;
int *y;
const int * const z = &x;

y = (int *)&x;
*y=11;
printf('%p %d ', y, *y);
printf('%p %d ', &x, x);
printf('%p %d ', z, *z);
return 0;
}

The output:

0012FF7C 11
0012FF7C 10
0012FF7C 11

The above output is when the program was compiled as cpp file and got
11
11
11
when compiled as "c" file.
Also
const int x=10;
int arr[x];
works with c++ compiler and not C.

My question is why is this mis-behaviour.

Shobhit

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vwprintw

curs_printw(3X) 														   curs_printw(3X)

NAME

       printw, wprintw, mvprintw, mvwprintw, vwprintw, vw_printw - print formatted output in curses windows

SYNOPSIS

       #include <curses.h>

       int printw(const char *fmt, ...);
       int wprintw(WINDOW *win, const char *fmt, ...);
       int mvprintw(int y, int x, const char *fmt, ...);
       int mvwprintw(WINDOW *win, int y, int x, const char *fmt, ...);
       int vwprintw(WINDOW *win, const char *fmt, va_list varglist);
       int vw_printw(WINDOW *win, const char *fmt, va_list varglist);

DESCRIPTION

       The  printw,  wprintw, mvprintw and mvwprintw routines are analogous to printf [see printf(3)].	In effect, the string that would be output
       by printf is output instead as though waddstr were used on the given window.

       The vwprintw and wv_printw routines are analogous to vprintf [see printf(3)] and perform a wprintw using a  variable  argument  list.   The
       third argument is a va_list, a pointer to a list of arguments, as defined in <stdarg.h>.

RETURN VALUE

       Routines that return an integer return ERR upon failure and OK (SVr4 only specifies "an integer value other than ERR") upon successful com-
       pletion.

       X/Open defines no error conditions.  In this implementation, an error may be returned if it cannot allocate enough memory  for  the  buffer
       used to format the results.  It will return an error if the window pointer is null.

PORTABILITY

       The  XSI  Curses  standard, Issue 4 describes these functions.  The function vwprintw is marked TO BE WITHDRAWN, and is to be replaced by a
       function vw_printw using the <stdarg.h> interface.  The Single Unix Specification, Version 2 states that vw_printw   is	preferred  to  vw-
       printw  since  the  latter  requires  including <varargs.h>, which cannot be used in the same file as <stdarg.h>.  This implementation uses
       <stdarg.h> for both, because that header is included in <curses.h>.

SEE ALSO

       curses(3X), printf(3), vprintf(3)

																   curs_printw(3X)