Hi,

 Can any one help me on the below program, as I need the missing element for array "a" to be printed when compared with array "b"

Program:

import std.stdio, std.array, std.algorithm;
string[] a = ["test1", "test2", "test4"];
string[] b = ["test2", "test4"];
void main ()
{
auto m = mismatch(a,b);
writeln(m[0]);
writeln(m[1]);
}

Output:
["test1", "test2", "test4"]
["test2", "test4"]

Required output: "test1"

From,
Vino.B

On Tuesday, 29 August 2017 at 18:20:38 UTC, Vino.B wrote:
> Hi,
>
>  Can any one help me on the below program, as I need the missing element for array "a" to be printed when compared with array "b"
>
> Program:
>
> import std.stdio, std.array, std.algorithm;
> string[] a = ["test1", "test2", "test4"];
> string[] b = ["test2", "test4"];
> void main ()
> {
> auto m = mismatch(a,b);
> writeln(m[0]);
> writeln(m[1]);
> }
>
> Output:
> ["test1", "test2", "test4"]
> ["test2", "test4"]
>
> Required output: "test1"
>
> From,
> Vino.B

The mismatch function doesn't work how your expecting it to. It compares the ith element in a with the ith element in b, until they encounter an element that is not equal. It then returns all elements including and beyond i, for both arrays. In this case the first element does not match, and therefore it returns the entire contents of both arrays.

On 08/29/2017 11:20 AM, Vino.B wrote:

> string[] a = ["test1", "test2", "test4"];
> string[] b = ["test2", "test4"];

> Required output: "test1"

You're looking for setDifference:

  https://dlang.org/phobos/std_algorithm_setops.html#.setDifference

Ali

On Tuesday, 29 August 2017 at 18:39:03 UTC, Ali Çehreli wrote:
> On 08/29/2017 11:20 AM, Vino.B wrote:
>
>> string[] a = ["test1", "test2", "test4"];
>> string[] b = ["test2", "test4"];
>
>> Required output: "test1"
>
> You're looking for setDifference:
>
>   https://dlang.org/phobos/std_algorithm_setops.html#.setDifference
>
> Ali

Hi,

 I tried the setDifference but does seem to be working as expected

import std.stdio, std.array, std.algorithm;
string[] a = ["test4", "test3", "test2", "test1"];
string[] b = ["test2", "test4"];
void main ()
{
auto m = setDifference(a,b);
writeln(m);
}

Output : Required output ["test3", "test1"]

["test3", "test2", "test1"]

From,
Vino.B

On Wednesday, 30 August 2017 at 06:16:16 UTC, Vino.B wrote:
> On Tuesday, 29 August 2017 at 18:39:03 UTC, Ali Çehreli wrote:
>> https://dlang.org/phobos/std_algorithm_setops.html#.setDifference


>  I tried the setDifference but does seem to be working as expected

From the documentation of setDifference: "The two ranges are assumed to be sorted by less."

In other words, you will need to sort your ranges first. Either pre-sort them as

    string[] a = ["test1", "test2", "test3", "test4"];
    string[] b = ["test2", "test4"]';

or call setDifference(a.sort(), b.sort()).

--
  Biotronic