Why doesn't IndexOf work with StringCompare?

Question

I get this error

    string v = "aeiou";
    foreach(int i in lokacija.Naziv) {
      if(v.indexOf(lokacija.Naziv[i], StringComparison.CurrentCultureIgnoreCase) = -1)
        s+=lokacija.Naziv[i];
    }

The error says "cannot convert from System.StringComparison to int". But I know there is an overload of the method indexOf(string) which accepts arguments of the type StringComparison. So how can I resolve this?

I'd guess that `lokacija.Naziv[i]` likely provides a `Char`. [`.IndexOf()`](https://msdn.microsoft.com/en-us/library/system.string.indexof.aspx) only accepts `StringComparison`s when the 1st argument is a `String`. — Jonathan Lonowski, Oct 01 '15 at 01:25
@JonathanLonowski it depends of the .NET Framework used. There **is** such a function in .NET Core 3.1: https://learn.microsoft.com/en-us/dotnet/api/system.string.indexof?view=netcore-3.1#System_String_IndexOf_System_Char_System_StringComparison_ — serge, Oct 25 '20 at 14:25

score 2 · Answer 1 · edited May 23 '17 at 10:27

2

First of all, you should be using == for comparison.

Second, all IndexOf overloads whose first parameter is a char, their second parameter is an int. That's why you get that error. In order to use the overload that receives a StringComparison, make that first parameter a string, like this:

if (v.indexOf(lokacija.Naziv[i].ToString(), StringComparison.CurrentCultureIgnoreCase) == -1)

BTW, are you trying to remove vowels from a string? I recommend you try this.

edited May 23 '17 at 10:27

Community

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answered Oct 01 '15 at 03:08

Andrew

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not quite true your second point. In .NET Core we have the overload `char, StringComparision` https://learn.microsoft.com/en-us/dotnet/api/system.string.indexof?view=netcore-3.1#System_String_IndexOf_System_Char_System_StringComparison_ – serge Oct 25 '20 at 14:23
Well, .NET Core Initial release: June 27, 2016, my bad for not knowing the future. – Andrew Oct 26 '20 at 12:03

score 0 · Answer 2 · answered Oct 01 '15 at 01:27

0

you loop seems strange... did you mean this?

foreach(string ssub in lokacija.Naziv) {
  if(v.indexOf(ssub, StringComparison.CurrentCultureIgnoreCase) = -1)
    s+=ssub;

answered Oct 01 '15 at 01:27

Hogan

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score 0 · Answer 3 · answered Oct 01 '15 at 01:27

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@Johnathan-Lonowski hit the nail on the head- you are getting this version of String.IndexOf, not this one, because you are looking for a character in a string, not an occurrence of one string in another.

answered Oct 01 '15 at 01:27

Chris Shain

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there **is** a function with `(char, ComparisonType)`, in .NET Core – serge Oct 25 '20 at 14:27

Why doesn't IndexOf work with StringCompare?

3 Answers3