Getting index of duplicate items in a list in c#

Question

I am looking for a way to get the index of all elements in a list from a keyword search within the list. So for example my list has:

Hello World
Programming          


        

Answer 1

searchInList.Select((value, index) => new {value, index})
    .Where(a => string.Equals(a.value, "Hello World"))
    .Select(a => a.index)

If you're trying to search for more than just "Hello World", you could do

searchInList.Select((value, index) => new {value, index})
    .Where(a => stringsToSearchFor.Any(s => string.Equals(a.value, s)))
    .Select(a => a.index)