using const

[lambs4]

Why won't this usage of const work? If I compile it as c++ is works. I'm using Borland C++ 4.5.

#include <stdio.h>
#include <conio.h>
const char K_ESC = 0x1B;

int main()
{

 char c;
 c = getch();
 switch(c)
 { case K_ESC : printf("You have escaped!");
	          break;
 }
getch();
}

[bigtamscot]

const char K_ESC = '0x1B'; /*note quotes*/

not sure of 0x1B for escape key try '\x1b'

[Shiro]

#define K_ESC '\1B'

By the way. Even a const char is a variable, although it may not be altered. The cases in the switch structure do really need real constants.

[bigtamscot]

have modified your program slightly

#include <stdio.h>
#include <conio.h>
#define K_ESC  '\x1B'

int main()
{

 char c;
 c = getch();
 if(c == K_ESC)
       printf("You have escaped!");

 else 
       printf("You didnot hit Esc");

getch();
return 0;
}

[Salem]

const has different meanings in C and C++

In C
  const char K_ESC = 0x1B;
All this means is that K_ESC should not be changed, and that the compiler should warn you if you try and do something like K_ESC++;

The case statement requires
  case constant-expression (eg. 2 + 3 - 4 )
but in your context, you have
  case identifier
and the compiler can't look inside that identifier at compile time to get the const value.

In C++
  const char K_ESC = 0x1B;
This really is a constant, and is somewhat akin to
  #define K_ESC 0x1B
but with all the advantages of type checking.