How to compare Chars in C# short way

Question

I'm wondering if there is a short way to compare one Char to many Chars. In my code I read a Key for Yes or No [Y/N] then i will check if the Char is 'Y' Or 'N'.

This is the Long Way:

if(myChar == 'n' || myChar == 'y')
{
....

It tried(didn't work):

if(myChar == ('n'|'y'))
{
.....

Can someone help?

I mean, if its just two expressions I don't see why you would need any short hand. An alternative would be to have an array of "allowed chars" and do a `Contains()`, but that seems overkill for something like this. — maccettura, Jun 26 '17 at 15:04

score 4 · Answer 1 · answered Jun 26 '17 at 15:04

4

Try looking in a collection:

HashSet<char> valid = new HashSet<char>() {
  'y', 'n', 'N', 'Y',
};

...

if (valid.Contains(myChar)) {
  ...
}

answered Jun 26 '17 at 15:04

Dmitry Bychenko

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Why not just a string instead of a Hashset? – Kenneth K. Jun 26 '17 at 15:06
@Kenneth K.: quite right, `if ("nNyY".Contains(myChar))`{...}` is possible, but I prefer `HashSet` for its *readability* (we have a collection of *valid* characters; if we want to add, say `T` `t` for true we know what to do) – Dmitry Bychenko Jun 26 '17 at 15:07
1

@GiladGreen Agreed, but O(1) for 4 characters isn't going to be very much of an impact. – Kenneth K. Jun 26 '17 at 15:08
Is it wrong to use: if ("ny".Contains(myChar.ToString().ToLower()))? – Sean Stayns Jun 26 '17 at 15:09
1

@Sean Stayn: it should be `if ("ny".Contains(char.ToLower(myChar))) {...}` – Dmitry Bychenko Jun 26 '17 at 15:11
Am I taking crazy pills? Or is a "Y/N" check really need to be this complex? Haha – maccettura Jun 26 '17 at 15:11
1

@DmitryBychenko Actually, if you want to be proper it should be `if ("ny".Contains(char.ToLowerInvariant(myChar)))` – Scott Chamberlain Jun 26 '17 at 15:39
@Scott Chamberlain: Agree; one should put `Invariant` in order to be on the safe side. – Dmitry Bychenko Jun 26 '17 at 15:45

score 2 · Answer 2 · answered Jun 26 '17 at 15:08

2

When the list of characters is short, use Contains method of string:

if ("yn".Contains(myChar)) {
    ...
}

answered Jun 26 '17 at 15:08

Sergey Kalinichenko

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Note, this will be a case sensitive compare. You will need to do `"YyNn".Contains(myChar)` or use `"yn".IndexOf(myChar, StringComparison.OrdinalIgnoreCase) >= 0)` – Scott Chamberlain Jun 26 '17 at 15:50
@ScottChamberlain This is absolutely true, if OP needs case-insensitive comparison, he would need to do one of the methods that you described. – Sergey Kalinichenko Jun 26 '17 at 16:09

How to compare Chars in C# short way

2 Answers2