How to replace some particular string in a list of type string using linq?

Question

Hi all I have list of type string with some items. i want to replace some items using linq, how can i do that? my below code is working fine but i want to do this in single line of code using the power of linq.

Here is my code :

List<string> listcolumns = columns.ToList();//Array to list

if (listcolumns.Contains("HowToReplace") && listcolumns.Contains("HowTo Replace"))
{
    int index = 0;
    index = listcolumns.IndexOf("HowToReplace");
    if (index > 0)
    {
        listcolumns.RemoveAt(index);
        listcolumns.Insert(index, "HowTo Replace");
    }
    index = listcolumns.IndexOf("HowToReplace");
    if (index > 0)
    {
        listcolumns.RemoveAt(index);
        listcolumns.Insert(index, "HowTo Replace");
    }
    columns = listcolumns.ToArray<string>();//List to array
}

Blau · Accepted Answer · 2011-11-09 10:02:37Z

22

With Linq:

listColumns.Select<string,string>(s => s == "HowToReplace" ? "HowTo Replace" : s).ToArray();

Without Linq:

 for (int i=0; i<listColumns.Length; i++) 
    if (ListColumns[i] == "HowToreplace") ListColumns[i] ="HowTo Replace");

edited Nov 9, 2011 at 10:02

answered Nov 9, 2011 at 9:51

Blau

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Comments

Muhammad Hasan Khan · Accepted Answer · 2011-11-09 10:01:11Z

8

static class LinqExtensions
{
    public static IEnumerable<T> Replace<T>(this IEnumerable<T> items, Predicate<T> condition, Func<T, T> replaceAction)
    {
        return items.Select(item => condition(item) ? replaceAction(item) : item);
    }
}

Then you can use it like so

var names = new[] { "Hasan", "Jack", "Josh" };
names = names.Replace(x => x == "Hasan", _ => "Khan").ToArray();

answered Nov 9, 2011 at 10:01

Muhammad Hasan Khan

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1 Comment

Blau Over a year ago

+1 Elegant and first time I see a lambda without params defined that way ... everyday I learn something new :)

Satpal · Accepted Answer · 2016-04-08 10:48:44Z

7

List<String> lstString = new List<string> { "find", "find1","find", "find2" };

//all 'find' will be replaced with 'replace'
lstString.Select(str=>str.Replace("find","replace"));

edited Apr 8, 2016 at 10:48

Satpal

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answered Nov 9, 2011 at 9:56

s_nair

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3 Comments

Blau Over a year ago

This is not doing the operation requested.

s_nair Over a year ago

@Blau: Herein I propose a solution which can be tailored further for any specific business problem.

Blau Over a year ago

hehehe, of course, but this question is specific enough... he wants to replace full strings, and replace method will replace substrings too... ;)

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