• bearophile (7/7) Nov 12 2010 Reading a bit about the C-like language used in the LoseThos Operating S...
• Adam D. Ruppe (10/11) Nov 12 2010 The only thing I can imagine using it for is checking the magic
• bearophile (4/6) Nov 12 2010 The author of that little operating system seems a quite odd person (eve...
• Ellery Newcomer (4/11) Nov 12 2010 It doesn't look like he says that 'ABC' is actually an integer.
• Rainer Deyke (5/7) Nov 12 2010 I seem to recall that this is feature is also present in C/C++, although
• Ellery Newcomer (11/16) Nov 12 2010 Oh wow.
• bearophile (4/6) Nov 13 2010 I see. The stream of C/C++ features that I discover never ends...

bearophile <bearophileHUGS lycos.com> writes:

Reading a bit about the C-like language used in the LoseThos Operating System,
I have found one thing.

In this language a single quote can encompass multiple characters. 'ABC' is
equal to 0x434241.

So it's not the same thing as D Hex Strings, because 'ABC' represents an
integral value, so it's a more like a base-256 integer literal :-)

So I guess '' is zero, equals to '\0' (currently in D '' gives a "unterminated
character constant" error).

What's the purpose of them?

Bye,
bearophile

Adam D. Ruppe <destructionator gmail.com> writes:

bearophile wrote:
 What's the purpose of them?

The only thing I can imagine using it for is checking the magic
number in a file header. Like 'ZM' for a DOS exe.

But I'd prefer to just use a regular string for it... an integer
would be easily wrong due to endianness issues. (In the DOS
exe the header actually says 'MZ' if you read the file from
left to right. The PNG magic number is '.PNG' left to right,
but as an integer literal, it would be backward 'GNP.')

Seems like more trouble than its worth to me, but maybe
I'm missing something too.

bearophile <bearophileHUGS lycos.com> writes:

Adam D. Ruppe:

 Seems like more trouble than its worth to me, but maybe
 I'm missing something too.

The author of that little operating system seems a quite odd person (even for
the flexible standards of the D newsgroups) so maybe you are missing nothing.

Bye,
bearophile

Ellery Newcomer <ellery-newcomer utulsa.edu> writes:

It doesn't look like he says that 'ABC' is actually an integer.

If he's just expressing a character string as a little endian integer 
(which you see a lot of in e.g. debuggers), then it makes sense.

On 11/12/2010 09:02 PM, bearophile wrote:
 Reading a bit about the C-like language used in the LoseThos Operating System,
I have found one thing.

 In this language a single quote can encompass multiple characters. 'ABC' is
equal to 0x434241.

 So it's not the same thing as D Hex Strings, because 'ABC' represents an
integral value, so it's a more like a base-256 integer literal :-)

 So I guess '' is zero, equals to '\0' (currently in D '' gives a "unterminated
character constant" error).

 What's the purpose of them?

 Bye,
 bearophile

Rainer Deyke <rainerd eldwood.com> writes:

On 11/12/2010 20:02, bearophile wrote:
 In this language a single quote can encompass multiple characters.
 'ABC' is equal to 0x434241.

I seem to recall that this is feature is also present in C/C++, although
I can't say that I've ever used it.


-- 
Rainer Deyke - rainerd eldwood.com

Ellery Newcomer <ellery-newcomer utulsa.edu> writes:

On 11/12/2010 11:28 PM, Rainer Deyke wrote:
 On 11/12/2010 20:02, bearophile wrote:
 In this language a single quote can encompass multiple characters.
 'ABC' is equal to 0x434241.

 I seem to recall that this is feature is also present in C/C++, although
 I can't say that I've ever used it.

Oh wow.

#include <stdlib.h>
#include <stdio.h>

void main(void){
     int i = 'ABC';
     printf("0x%x\n", i);
}

yields:

0x414243

And that's backwards from what I would have expected

bearophile <bearophileHUGS lycos.com> writes:

Rainer Deyke:

 I seem to recall that this is feature is also present in C/C++, although
 I can't say that I've ever used it.

I see. The stream of C/C++ features that I discover never ends...

Bye,
bearophile