Is there a read source of example code in D? Something a little more extensive that those that come with the compiler without being horribly complex. Just some worked examples of using the various new (relative to C) language features.

My current block is with hashes (associative arrays).

I see from the wc sample that you can iterate a hash by

1) retrieving an array of all the keys in the hash
2) iterating that array using a numeric index
3) using the result (key) from that to index into the hash and retrieve the
corresponding value.

That works fine, but it requires the duplication of the storage required for the keys, which is expensive for large hashes.

I was looking for an iterator something like perl5's "each" keyword? I such a thing possible, planned, hiding or just out of the question?



Regards, anon.

Anon. wrote:
> Is there a read source of example code in D? Something a little more extensive
> that those that come with the compiler without being horribly complex. Just some
> worked examples of using the various new (relative to C) language features. 
> 
> My current block is with hashes (associative arrays). 
> 
> I see from the wc sample that you can iterate a hash by
> 
> 1) retrieving an array of all the keys in the hash
> 2) iterating that array using a numeric index
> 3) using the result (key) from that to index into the hash and retrieve the
> corresponding value.
> 
> That works fine, but it requires the duplication of the storage required for the
> keys, which is expensive for large hashes. 
> 
> I was looking for an iterator something like perl5's "each" keyword? I such a
> thing possible, planned, hiding or just out of the question?
> 
> 
> 
> Regards, anon.

Please... pick at  http://www.digitalmars.com/d/arrays.html
and learn about Associative Arrays. (not require duplication)... read de wc2.d example :-)

About D examples code, if you know about C, only read the language specifications there are a lot of examples (not full programs) but it's very easy to write your owns.

More: pick at D links there are many sites with examples and tutorials


regards

Julio Jiménez

In article <c258cm$1qu7$1@digitaldaemon.com>, =?ISO-8859-1?Q?Julio_Jim=E9nez?= says...
>
>Anon. wrote:
>> 
>> I see from the wc sample that you can iterate a hash by
>> 
>> 1) retrieving an array of all the keys in the hash
>> 2) iterating that array using a numeric index
>> 3) using the result (key) from that to index into the hash and retrieve the
>> corresponding value.

that's old.

(from memory)
char[][char[]] hash;
foreach ( char[] value ; hash.values )
{
   printf("value is %.*s\n", value);
}

check http://www.digitalmars.com/d/statement.html#foreach

it's a pity associative arrays are not supported with the other
foreach version: foreach ( int|uint, type ; array )
it could be:
foreach ( char[] key, char[] value ; hash ) // not valid

Ant

Ant wrote:
> In article <c258cm$1qu7$1@digitaldaemon.com>, =?ISO-8859-1?Q?Julio_Jim=E9nez?=
> says...
> 
>>Anon. wrote:
>>
>>>I see from the wc sample that you can iterate a hash by
>>>
>>>1) retrieving an array of all the keys in the hash
>>>2) iterating that array using a numeric index
>>>3) using the result (key) from that to index into the hash and retrieve the
>>>corresponding value.
> 
> 
> that's old.
> 
> (from memory)
> char[][char[]] hash;
> foreach ( char[] value ; hash.values )
> {
>    printf("value is %.*s\n", value);
> }
> 
> check http://www.digitalmars.com/d/statement.html#foreach
> 
> it's a pity associative arrays are not supported with the other
> foreach version: foreach ( int|uint, type ; array )
> it could be:
> foreach ( char[] key, char[] value ; hash ) // not valid
> 
> Ant
> 

I foreach over associative arrays all the time. There's even an example   http://www.digitalmars.com/d/statement.html#foreach :

   double[char[]] a; // index type is char[], value type is double
   ...
   foreach (char[] s, double d; a)
   {
      printf("a['%.*s'] = %g\n", s, d);
   }


-- 
Christopher E. Miller

In article <c25b2g$1vu0$1@digitaldaemon.com>, Vathix says...
>
>
>I foreach over associative arrays all the time. There's even an example
>   http://www.digitalmars.com/d/statement.html#foreach :
>
>    double[char[]] a; // index type is char[], value type is double
>    ...
>    foreach (char[] s, double d; a)
>    {
>       printf("a['%.*s'] = %g\n", s, d);
>    }

It is on the manuals!
I just check the manuals before posting... :(
need to check my eyes

thanks.

Ant

The wc2.d code: (from dmd examples)


import std.c.stdio;
import std.file;

int main (char[][] args)
{
    int w_total;
    int l_total;
    int c_total;
    int[char[]] dictionary;

    printf("   lines   words   bytes file\n");
    foreach (char[] arg; args[1 .. args.length])
    {
	char[] input;
	int w_cnt, l_cnt, c_cnt;
	int inword;
	int wstart;

	input = cast(char[])std.file.read(arg);

	for (int j = 0; j < input.length; j++)
	{   char c;

	    c = input[j];
	    if (c == '\n')
		++l_cnt;
	    if (c >= '0' && c <= '9')
	    {
	    }
	    else if (c >= 'a' && c <= 'z' ||
		c >= 'A' && c <= 'Z')
	    {
		if (!inword)
		{
		    wstart = j;
		    inword = 1;
		    ++w_cnt;
		}
	    }
	    else if (inword)
	    {	char[] word = input[wstart .. j];

		dictionary[word]++;
		inword = 0;
	    }
	    ++c_cnt;
	}
	if (inword)
	{   char[] w = input[wstart .. input.length];
	    dictionary[w]++;
	}
	printf("%8lu%8lu%8lu %.*s\n", l_cnt, w_cnt, c_cnt, arg);
	l_total += l_cnt;
	w_total += w_cnt;
	c_total += c_cnt;
    }

    if (args.length > 2)
    {
	printf("--------------------------------------\n%8lu%8lu%8lu total",
	    l_total, w_total, c_total);
    }

    printf("--------------------------------------\n");

    foreach (char[] word1; dictionary.keys.sort)
    {
	printf("%3d %.*s\n", dictionary[word1], word1);
    }
    return 0;
}

In article <c25b2g$1vu0$1@digitaldaemon.com>, Vathix says...
>
>Ant wrote:
>> In article <c258cm$1qu7$1@digitaldaemon.com>, =?ISO-8859-1?Q?Julio_Jim=E9nez?= says...
>> 
>>>Anon. wrote:
>>>
>>>>I see from the wc sample that you can iterate a hash by
>>>>
>>>>1) retrieving an array of all the keys in the hash
>>>>2) iterating that array using a numeric index
>>>>3) using the result (key) from that to index into the hash and retrieve the
>>>>corresponding value.
>> 
>> 
>> that's old.
>> 
>> (from memory)
>> char[][char[]] hash;
>> foreach ( char[] value ; hash.values )
>> {
>>    printf("value is %.*s\n", value);
>> }
>> 
>> check http://www.digitalmars.com/d/statement.html#foreach
>> 
>> it's a pity associative arrays are not supported with the other
>> foreach version: foreach ( int|uint, type ; array )
>> it could be:
>> foreach ( char[] key, char[] value ; hash ) // not valid
>> 
>> Ant
>> 
>
>I foreach over associative arrays all the time. There's even an example
>   http://www.digitalmars.com/d/statement.html#foreach :
>
>    double[char[]] a; // index type is char[], value type is double
>    ...
>    foreach (char[] s, double d; a)
>    {
>       printf("a['%.*s'] = %g\n", s, d);
>    }
>
Great! It seemed strange that a language that is so well thought through in almost every respect should require the contortions shown in the word count example at the end of the Arrays section of the manual.

char[][] keys = dictionary.keys;// find all words in dictionary[]
for (int i = 0; i < keys.length; i++)
{   char[] word;

word = keys[i];
printf("%3d %.*s\n", dictionary[word], word);
}

I (now) see that the wc2.d in the samples/d directory uses foreach. Maybe this will act as a reminder for someone to update that page of the manual.

FWIW. I still that that an iterator would make sense. Sometimes its isn't convenient to process all the keys of a hash in one loop. A pair of methods:

aarray.first
aarray.next

maybe?

Thanks all.

Anon.



>
>-- 
>Christopher E. Miller

In article <c258cm$1qu7$1@digitaldaemon.com>, =?ISO-8859-1?Q?Julio_Jim=E9nez?= says...
>
>Anon. wrote:
>> Is there a read source of example code in D? Something a little more extensive that those that come with the compiler without being horribly complex. Just some worked examples of using the various new (relative to C) language features.
>> 
>> My current block is with hashes (associative arrays).
>> 
>> I see from the wc sample that you can iterate a hash by
>> 
>> 1) retrieving an array of all the keys in the hash
>> 2) iterating that array using a numeric index
>> 3) using the result (key) from that to index into the hash and retrieve the
>> corresponding value.
>> 
>> That works fine, but it requires the duplication of the storage required for the keys, which is expensive for large hashes.
>> 
>> I was looking for an iterator something like perl5's "each" keyword? I such a thing possible, planned, hiding or just out of the question?
>> 
>> 
>> 
>> Regards, anon.
>
>Please... pick at  http://www.digitalmars.com/d/arrays.html

It was "Associative Array Example: word count" at the end of that very page that gave me my mistaken impression :)

>and learn about Associative Arrays. (not require duplication)... read de wc2.d example :-)
>
>About D examples code, if you know about C, only read the language specifications there are a lot of examples (not full programs) but it's very easy to write your owns.
>

I've always found it quicker to learn a language by reading through code written by other people with a reasonable amount of expertise than to learn it by piecing together my own code by leaping all over the manula to pick up he pieces. The latter technique tends to lead to mistaken impressions and bad habits.

>
>More: pick at D links there are many sites with examples and tutorials
>

If you could point me at a few of tehse many sites, that would be really useful.

>
>regards
>
>Julio Jiménez
>

regards, Anion

Anon. wrote:
...

> 
> 
> If you could point me at a few of tehse many sites, that would be really useful.
> 
> 
>>regards
>>
>>Julio Jiménez
>>
> 
> 
> regards, Anion
> 
> 

http://dui.sourceforge.net/
you can learn about classes and interfacing to C libraries

http://int19h.tamb.ru/
some projects and examples

http://jcc_7.tripod.com/d/tutor/
Simple D tutorial

http://www.dprogramming.com/
Little tutorial and some projects

http://www.codemoon.com/cm/dpage.php
Programs in D


About the wc.d example, remember it's only an example; not the better way to do that.... wc2.d is a little better, but an example too.

D give you the freedom to do what you need in your own way.
Look at dmd/src/phobos/internal/aaA.d (Implementation of associative array)
you can study it and implement the functions you need ;-)
No need to wait another one write it for you!



Regards, Julio

In article <c246jl$301q$1@digitaldaemon.com>, Anon. says...
>
>Is there a read source of example code in D? Something a little more extensive that those that come with the compiler without being horribly complex. Just some worked examples of using the various new (relative to C) language features.

I would like to see a horribly complex problem solved with the full treatment in C++ and D side by side.  When I say nontrivial, I mean, I've seen the text-processing stuff and it's some nice syntax, but I could use perl for that.

I need to see something big that would require design patterns in C++.  D seems to automatically solve some major problems, like header dependencies that would require specific techniques to handle when writing C++.  Good job.  but there are a lot of unexpected interactions among language features that have been found and the C++ standard has at least tried to address. I'm not giving up on C++ yet.  If D can do better than the examples given in "Modern C++ Design", I'm listening.