Using select information from array

Question

I have a string array of the form [a b, a b, a b,...] and I want to create a new array of just the b values. I have tried a .split(" ") but it keeps coming up with an index outside the bounds of the array error.

for (int sequence = 0; sequence < FileIndex.Length; sequence++)
                    {
                        string[] SplitIndex = FileIndex[sequence].Split(' ');
                        sequence++;
                        WriteLine(SplitIndex[sequence]);
                     }

sequence++ inside The for loop is not needed. That will increase the value of sequence twice on each iteration — Chetan
– Chetan, Commented Oct 15, 2019 at 0:41

kkica · Accepted Answer · 2019-10-15 00:43:33Z

0

for (int sequence = 0; sequence < FileIndex.Length; sequence++)
{
    string[] SplitIndex = FileIndex[sequence].Split(' ');
    sequence++;
    WriteLine(SplitIndex[1]);
}

Once you split, in the SplitIndex you will have 2 elements: "a" and "b". If you want to access "b" you will have to use SplitIndex[1]. You are currently using SplitIndex[sequence]

Also, you have sequence++ twice. One in the for statement, and one inside the loop. You should remove it from the loop.

edited Oct 15, 2019 at 0:43

answered Oct 15, 2019 at 0:30

kkica

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3 Comments

tmaj Over a year ago

This will not work because of the extra sequence++ inside for.

Callum McNeilage Over a year ago

This works fine but it produces 8 leading spaces which I can't get rid of so that I can run a comparison against another variable

kkica Over a year ago

@tymtam I have already edited for the sequence++ dublication before you added your comment. CallumMcNeilage I dont know why you have this problem. Perhaps you should tell me what FileIndex[sequence] shows and if it has more than 1 space. You can always use TrimStart() to remove the spaces

RoadRunner · Accepted Answer · 2019-10-15 01:16:56Z

0

You could also use LINQ here:

using System.Linq;

...

var stringArray = new string[] { "a b", "a b", "a b" };

var result = stringArray
    .Select(str => str.Split(' ').Last())
    .ToArray();

Console.WriteLine("{ " + string.Join(", ", result) + " }");
// { b, b, b }

Explanation:

Select every element in the array with Enumerable.Select()
Split each string with String.Split() and take the last element with Enumerable.Last(). You could also just index the second element with [1] here as well.
Convert the result to an array with List.ToArray(). Optionally you could just leave the result as an IEnumerable<string> as well.

edited Oct 15, 2019 at 1:16

answered Oct 15, 2019 at 1:08

RoadRunner

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Comments

tmaj · Accepted Answer · 2019-10-15 01:30:01Z

0

`for` way

Remove sequence++;
Change WriteLine(SplitIndex[sqequence]); to WriteLine(SplitIndex[1]);

for (int sequence = 0; sequence < FileIndex.Length; sequence++)
{
  string[] SplitIndex = FileIndex[sequence].Split(' ');
  //sequence++;
  WriteLine(SplitIndex[1]);
}

Linq way

//Note: no error handling
var bees = FileIndex.Select(fi => fi.Split(' ')[1]);

You can add error handling

var bees = test.Select(fi => fi.Split(' ', StringSplitOptions.RemoveEmptyEntries).Skip(1).FirstOrDefault() ?? "'No b!'" );

Test

var test = new string[] { "a a", "a b", "a c", "a ", "" };

var bees = test.Select(fi => fi.Split(' ', StringSplitOptions.RemoveEmptyEntries).Skip(1).FirstOrDefault() ?? "'No b!'" );

Console.WriteLine(string.Join(" ", bees));

a b c 'No b!' 'No b!'

edited Oct 15, 2019 at 1:30

answered Oct 15, 2019 at 1:09

tmaj

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