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digitalmars.D.learn - Missing array element

reply Vino.B <vino.bheeman hotmail.com> writes:
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
Aug 29
next sibling parent Francis Nixon <13nixonf gmail.com> writes:
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.
Aug 29
prev sibling parent reply =?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:
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
Aug 29
parent reply Vino.B <vino.bheeman hotmail.com> writes:
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
Aug 29
parent Biotronic <simen.kjaras gmail.com> writes:
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
Aug 30