Remove duplicate strings in list using C# / LinQ but ignore case

Question

With the list:

"A", "Bb", "C", "a", "d", "bb"

How can I use LinQ to remove duplicates while ignoring casing?

the output here should be:

"C", "d"

Possible duplicate of [LINQ Distinct operator, ignore case?](https://stackoverflow.com/questions/283063/linq-distinct-operator-ignore-case) — D-Shih, Nov 07 '18 at 05:27
yes, I think you're right. And the solution there is shorter too. — Thomas, Nov 07 '18 at 12:28

score 7 · Accepted Answer · answered Nov 07 '18 at 05:11

7

try this

  var result = testList
               .GroupBy(item => item, StringComparer.OrdinalIgnoreCase)
               .Where(g => g.Count() == 1)
               .Select(g => g.Key)
               .ToList();

answered Nov 07 '18 at 05:11

Sooriya Dasanayake

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score 2 · Answer 2 · answered Nov 07 '18 at 05:10

2

Use can use the GroupBy method with one of the IgnoreCase string comparers, then select only those groups consisting of a single element

.GroupBy(_ => _, StringComparer.CurrentCultureIgnoreCase)
.Where(_ => _.Count() == 1)

answered Nov 07 '18 at 05:10

Klaus Gütter

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1

append `.Select(_ => _.Key).ToList();` to get the output the OP is after – jazb Nov 07 '18 at 05:17

score 0 · Answer 3 · answered Nov 07 '18 at 05:41

You can use GroupBy() with the StringComparer.CurrentCultureIgnoreCase option as follows:

List<String> data = new List<String>() { "A", "Bb", "C", "a", "d", "bb" };
List<String> newData = data.GroupBy(x => x, StringComparer.CurrentCultureIgnoreCase)
    .Where(el => el.Count() == 1)
    .Select(el => el.Key)
    .ToList();

Remove duplicate strings in list using C# / LinQ but ignore case

3 Answers3