• alexander.panek (23/23) Sep 07 2003 hi,
• Mike Wynn (12/41) Sep 07 2003 you cant do this as foo is null (foo.length == 0)
• Farmer (16/45) Sep 08 2003 I think this won't work: Since foo is null you cannot append or resize i...
• Mike Wynn (26/76) Sep 08 2003 have you tried;
• Carlos Santander B. (32/32) Sep 08 2003 "Mike Wynn" wrote in message
• Farmer (27/29) Sep 09 2003 I'm sorry, I had better done so.

"alexander.panek" <alexander.panek brainsware.org> writes:

hi,

there is a notice in the D reference, that this is not possible:

	int[] foo;
	int	i;

	foo[0] = 1;	
	foo[1] = 2;
	foo[2] = 3;
	foo[3] = 4;
	.
	.

	i = foo[3];

first, why causes this an error and second, why leads this into an error 
too:
	
	//XML is my class
	XML _xml;
	int i;	
	_xml = new XML(args[i]);

how could i program this without any arrayboundserror?

thx, alex

(p.s. sorry for my bad english.)
-- 
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/

Mike Wynn <mike l8night.co.uk> writes:

alexander.panek wrote:
 hi,
 
 there is a notice in the D reference, that this is not possible:
 
     int[] foo;

foo is 'null'

     int    i;
 
     foo[0] = 1;   

  you cant do this as foo is null (foo.length == 0)

     foo[1] = 2;
     foo[2] = 3;
     foo[3] = 4;
     .
     .
 
     i = foo[3];

try
foo.length = 4; (foo now has 4 elements). {0..3}
or
foo ~= 1;
foo ~= 2;
..etc..
you can ~= (append) to a null array


 
 first, why causes this an error and second, why leads this into an error 
 too:
     
     //XML is my class
     XML _xml;
     int i;   
     _xml = new XML(args[i]);
 
 how could i program this without any arrayboundserror?

set i to a value! did you want to pass an element of args or the whole 
array ?

 
 thx, alex
 
 (p.s. sorry for my bad english.)

Farmer <itsFarmer. freenet.de> writes:

Mike Wynn <mike l8night.co.uk> wrote in news:bjg6lu$1164$1 digitaldaemon.com:

 alexander.panek wrote:
 hi,
 
 there is a notice in the D reference, that this is not possible:
 
     int[] foo;

 
 foo is 'null'
 
     int    i;
 
     foo[0] = 1;   

   you cant do this as foo is null (foo.length == 0)
 
     foo[1] = 2;
     foo[2] = 3;
     foo[3] = 4;
     .
     .
 
     i = foo[3];

 
 try
 foo.length = 4; (foo now has 4 elements). {0..3}
 or
 foo ~= 1;
 foo ~= 2;
 ..etc..
 you can ~= (append) to a null array

I think this won't work: Since foo is null you cannot append or resize it.

One could either create a static array:
     int[4] foo;
	int	i;

	foo[0] = 1;	
	foo[1] = 2;
	foo[2] = 3;
	foo[3] = 4;


or use a dynamic array, that is initially empty (but not null).

     int[] foo=new int[0];
	int	i;

	foo ~= 1;	
	foo ~= 2;
	foo ~= 3;
	foo ~= 4;

Mike Wynn <mike l8night.co.uk> writes:

Farmer wrote:
 Mike Wynn <mike l8night.co.uk> wrote in news:bjg6lu$1164$1 digitaldaemon.com:
 
 
alexander.panek wrote:

hi,

there is a notice in the D reference, that this is not possible:

    int[] foo;

foo is 'null'


    int    i;

    foo[0] = 1;   

  you cant do this as foo is null (foo.length == 0)


    foo[1] = 2;
    foo[2] = 3;
    foo[3] = 4;
    .
    .

    i = foo[3];

try
foo.length = 4; (foo now has 4 elements). {0..3}
or
foo ~= 1;
foo ~= 2;
..etc..
you can ~= (append) to a null array

 
 
 I think this won't work: Since foo is null you cannot append or resize it.
 
 or use a dynamic array, that is initially empty (but not null).
 
      int[] foo=new int[0];
 	int	i;
 
 	foo ~= 1;	
 	foo ~= 2;
 	foo ~= 3;
 	foo ~= 4;
 

have you tried;
int[] foo;
foo ~= 1;

or even foo = new int[0];
if ( foo === null ) { printf( "foo is null"); }

just try ......

import c.stdio;

int main( char[][] args ) {
	int[] foo;
	int[] bar;
	foo = null; // force null;
	foo ~= 1;
	printf( "foo.length=%d\n", foo.length );
	printf( "foo[0] = %d\n", foo[0] );
	bar = new int[0];
	if ( bar === null ) { printf( "bar is null\n"); }
	return 0;
}

--------
on linux I get
foo.length=1
foo[0] = 1
bar is null

(the same as I used to get on windows)
if your going to post at least try out some code!

"Carlos Santander B." <carlos8294 msn.com> writes:

"Mike Wynn" <mike l8night.co.uk> wrote in message
news:bjiu9j$207p$1 digitaldaemon.com...
| if your going to post at least try out some code!
|

At least lately (one week, maybe two) we haven't had any C++ code.
I agree with Mike: when we post code ideas we should try to do it in D, or
some sort of pseudo D at least. It'll even help yourselves: you'll become
familiar with, and if you make any mistakes, maybe someone will correct it.
Also, when new people come they'll see more D code and will notice we're
using it.
Also, it's good to try to give a "D flavour" to the code. eg: Daniel said it
was better to use ~= instead of += in I-don't-remember-exactly-what-post.
Also ("also" day for me :) ) try the compiler: "does D support this? does D
support that?". Try it! (no offence intended)

-------------------------
Carlos Santander
"Mike Wynn" <mike l8night.co.uk> wrote in message
news:bjiu9j$207p$1 digitaldaemon.com...
| if your going to post at least try out some code!
|

At least lately (one week, maybe two) we haven't had any C++ code.
I agree with Mike: when we post code ideas we should try to do it in D, or
some sort of pseudo D at least. It'll even help yourselves: you'll become
familiar with, and if you make any mistakes, maybe someone will correct it.
Also, when new people come they'll see more D code and will notice we're
using it.
Also, it's good to try to give a "D flavour" to the code. eg: Daniel said it
was better to use ~= instead of += in I-don't-remember-exactly-what-post.
Also ("also" day for me :) ) try the compiler: "does D support this? does D
support that?". Try it! (no offence intended)

-------------------------
Carlos Santander

Farmer <itsFarmer. freenet.de> writes:

Mike Wynn <mike l8night.co.uk> wrote in news:bjiu9j$207p$1 digitaldaemon.com:

 if your going to post at least try out some code!
 

I'm sorry, I had better done so. 

You're right, your code works fine.


DMD doesn't care whether you write
   int[] foo = new int[0];
or
   int[] foo;
Both produces the same code (even if optimization is turned off).



I'm not happy with the current situation:
1)I can't distinguish between an empty array and a null array. Which is 
sometimes handy.


2)Arrays/Slices seem a bit erratic with regard to beeing null or empty.
Here's an example:

void main()
{
   int[] foo = new int[0];
   if (foo === null) printf("foo is null\n");

   int[] foo2 = new int[1];
   int[] emptySlice = foo2[0..0];

   if (emptySlice !== null) printf("emptySlice is NOT null\n");

   emptySlice.length = 0;
   if (emptySlice === null) printf("emptySlice is now null\n");
}

prints:

foo is null
emptySlice is NOT null
emptySlice is now null