type casting and const

Thread View: net.lang.c++

2 messages

[T] Back to Threads [V] Tree View [G] Group Articles

2 total messages Started by Tom Lanning Wed, 05 Mar 1986 00:12

#52

Author: Tom Lanning
Date: Wed, 05 Mar 1986 00:12

10 lines
1022 bytes

	I have a class, "string", that can be converted to "char*".  I
want the converted object to be "readonly", i.e. "const".  I have been
using "operator char* ()", but would like to know if there is a way
to get "const char*".  I do not want to use intermediate types since
I want to use "string" and "const char*" together without explict type
casting.  Any help would be appreciated, thanks.
-- 

  Tom Lanning   AT&T Bell Laboratories   Columbus OH   43213     614-860-4153

Re: type casting and const

#71

Author: aglew
Date: Fri, 07 Mar 1986 03:14

28 lines
1845 bytes

>/* Written  6:12 pm  Mar  4, 1986 by trl@cbrma.UUCP in ccvaxa:net.lang.c++ */
>/* ---------- "type casting and const" ---------- */
>
>	I have a class, "string", that can be converted to "char*".  I
>want the converted object to be "readonly", i.e. "const".  I have been
>using "operator char* ()", but would like to know if there is a way
>to get "const char*".  I do not want to use intermediate types since
>I want to use "string" and "const char*" together without explict type
>casting.  Any help would be appreciated, thanks.
>-- 
>
>  Tom Lanning   AT&T Bell Laboratories   Columbus OH   43213     614-860-4153
>/* End of text from ccvaxa:net.lang.c++ */

This raises another interesting point: is it possible to require 
read-only-ness as part of the description of the type to which a pointer
refers? Verbosely "pointer to const int", *(const int), so that 
	int i;
	const int j = 666;
	int *pv;
	const int *pc;			// or something like
	pv = &i;  *pv = 1;	//succeeds
	pv = &j;  *pv = 2;	// should fail, perhaps at compile time?
	pc = &i;  *pc = 3;	// should fail AT COMPILE TIME
	pc = &j;  *pc = 4;	// ditto.

Or is the only way to define a new class, overloading assignment, etc?

Thread Navigation

This is a paginated view of messages in the thread with full content displayed inline.

Messages are displayed in chronological order, with the original post highlighted in green.

Use pagination controls to navigate through all messages in large threads.

Back to All Threads