Prepend/Append string for each element in a string array

Question

I have some code as below:

char[] separator = { ',' };

String[] idList = m_idsFromRequest.Split(separator);  //m_idsFromRequest="1,2....";
List<string> distinctIdList = idList.Distinct().ToList();
m_distinctIdList = distinctIdList.ToArray();
m_idsFromRequest = string.Join(" ", distinctIdList);

currently m_idsFromRequest = ["1","2".........."] is as such. I want to make it ["0|1","0|2".........."] like append "0|" in each element . I wanted to know id I could do it without the foreach loop.

FYI your original code can be reduced to m_idsFromRequest = string.Join(" ", m_idsFromRequest.Split(separator).Distinct()); and you'll avoid creating the unneeded intermediate list and array. — juharr
– juharr, Commented May 12, 2021 at 14:08
Also if your string has brackets at both ends then something like ["1","1"] would not change as the distinct is being applied to values of ["1" and '"1"] — juharr
– juharr, Commented May 12, 2021 at 14:09
sure I'll look into that. there is some in-between jugglery done with the intermediate data so I've just put up the overall stuff. besides i ain't allowed to touch much code as per my seniors. — Shalini Raj
– Shalini Raj, Commented May 12, 2021 at 14:11
Note the answers below are assuming you're starting with a string like 1,2,3 and not a string like ["1","2","3"] and would not work with the later values so the exact format of the initial string is important here. — juharr
– juharr, Commented May 12, 2021 at 14:13

mokh223 · Accepted Answer · 2021-05-12 14:14:47Z

4

char[] separator = { ',' };
string m_idsFromRequest = "1,2,3,4,5,6";
String[] idList = m_idsFromRequest.Split(separator);  //m_idsFromRequest="1,2....";
List<string> distinctIdList = idList.Distinct().Select(t => "0|" + t).ToList();
m_idsFromRequest = string.Join(",", distinctIdList);

Just added the .Select() after .Distinct(). Inside the .Select you can transform each of the item in the list.

Apart from that i also added "," in your string.Join. Because you want it to be join by comma.

edited May 12, 2021 at 14:14

answered May 12, 2021 at 14:11

mokh223

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1 Comment

mokh223 Over a year ago

@Martin i have added the answer

Tim Schmelter · Accepted Answer · 2021-05-12 14:17:57Z

4

You can use Select and String.Join:

var idsPrependedWithZero = m_idsFromRequest.Split(separator)
    .Distinct() // same as in your code
    .Select(id => $"0|{id}");
string result = string.Join(",", idsPrependedWithZero);

edited May 12, 2021 at 14:17

answered May 12, 2021 at 14:09

Tim Schmelter

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2 Comments

juharr Over a year ago

You forgot the Distinct

Tim Schmelter Over a year ago

@juharr: where OP mentioned that they must be unique? Edit: I see. Fixed

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