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A converting problem in using "among" with arrays
Jul 29, 2022
pascal111
Jul 29, 2022
Andrey Zherikov
Jul 29, 2022
pascal111
Jul 29, 2022
H. S. Teoh
Jul 29, 2022
Salih Dincer
Jul 29, 2022
ryuukk_
July 29, 2022
Gravatar of pascal111Posted by pascal111Reply
pascal111
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I next code, we have a data type problem "54.among(to!uint10).writeln;":

module main;

import std.stdio;
import std.string;
import std.conv;
import dcollect;
import std.math;
import std.algorithm;

int main(string[] args)
{
    int[] x=[23, 34,-88, 54, -90, -34];

    auto y=x.filter!(a=>a<0);

    foreach(i; y)
        i.write(", ");

    54.among(to!uint[10](y)).writeln;

	return 0;
}

Error message:
"hello.d|19|error: only one index allowed to index void|"

July 29, 2022
Gravatar of Andrey ZherikovPosted by Andrey Zherikov
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Andrey Zherikov
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On Friday, 29 July 2022 at 22:09:47 UTC, pascal111 wrote:

>

I next code, we have a data type problem "54.among(to!uint10).writeln;":

module main;

import std.stdio;
import std.string;
import std.conv;
import dcollect;
import std.math;
import std.algorithm;

int main(string[] args)
{
    int[] x=[23, 34,-88, 54, -90, -34];

    auto y=x.filter!(a=>a<0);

    foreach(i; y)
        i.write(", ");

    54.among(to!uint[10](y)).writeln;

	return 0;
}

Error message:
"hello.d|19|error: only one index allowed to index void|"

Did you mean to!(uint[10])(y)? This converts to uint[10].

July 29, 2022
Gravatar of pascal111Posted by pascal111
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pascal111
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Posted in reply to Andrey Zherikov


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On Friday, 29 July 2022 at 22:12:54 UTC, Andrey Zherikov wrote:

>

On Friday, 29 July 2022 at 22:09:47 UTC, pascal111 wrote:

>

I next code, we have a data type problem "54.among(to!uint10).writeln;":

module main;

import std.stdio;
import std.string;
import std.conv;
import dcollect;
import std.math;
import std.algorithm;

int main(string[] args)
{
    int[] x=[23, 34,-88, 54, -90, -34];

    auto y=x.filter!(a=>a<0);

    foreach(i; y)
        i.write(", ");

    54.among(to!uint[10](y)).writeln;

	return 0;
}

Error message:
"hello.d|19|error: only one index allowed to index void|"

Did you mean to!(uint[10])(y)? This converts to uint[10].

I want searching for value 54 in array y "54.among(y).writeln;", but it seems compiler complaints because the data type is "int[]", so I tried to convert "y" to "uint[]".

July 29, 2022
Gravatar of Salih DincerPosted by Salih Dincer
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Salih Dincer
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On Friday, 29 July 2022 at 22:09:47 UTC, pascal111 wrote:

>

Error message:
"hello.d|19|error: only one index allowed to index void|"

 
import std.stdio;

void main() {
  int[] y = [-90, -88, -34]; /* ok but no
  compile y.to!uint[10] */
  enum len = 10;
  y.length = len;
  int[len] v = y;
  v.writeln; // [-90, -88, -34, 0, 0, 0, 0, 0, 0, 0]

  int x = 54; /* or may be -54
  because: */ assert(is(typeof(x) == int));

  auto z = x.to!uint; /*)) ok but not be -54
  because: */ assert(is(typeof(z) == uint));

  x.writeln(" == ", z); /* but no
  compile z = -54 */
  x = -54;
}

SDB@79

July 29, 2022
Gravatar of H. S. TeohPosted by H. S. Teoh
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H. S. Teoh
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On Fri, Jul 29, 2022 at 10:32:11PM +0000, pascal111 via Digitalmars-d-learn wrote: [...]
> I want searching for value 54 in array y "54.among(y).writeln;", but it seems compiler complaints because the data type is "int[]", so I tried to convert "y" to "uint[]".

You're using the wrong function; .among is intended to be used in the cases where the list of values to search for are fixed or known at compile-time.

If the values to search for changes at runtime, you want .canFind instead. For example:

	if ([1, 2, 3, 4].canFind(3))
		writeln("found it!");

Or use .find if you need to retrieve the found value (e.g., if it's a structure and you matched on only one field).

	auto r = [ 1, 2, 3, 4 ].find(3);
	assert(r.front == 3);


T

-- 
It's amazing how careful choice of punctuation can leave you hanging:
July 29, 2022
Gravatar of ryuukk_Posted by ryuukk_
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ryuukk_
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FYI, you can use the markdown code tag so your code is properly rendered when viewed from the forums (make sure to tick the "Enable Markdown", right next to Send)

    ```D
    void my_function()
    {
    }
    ```

it'll be rendered like this:

void my_function()
{
}