C# what does (bool ? string : string) do?

Question

Looking for help working out what the code in return does / is called

private string MakeOrderKey(string s1, string s2)
{
   bool b = (string.Compare(s1, s2) < 0);
   return ((b ? s1 : s2) +  "/" + (b ? s2 : s1));
}

It's called a [Ternary operator](https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/conditional-operator) — Alexey S. Larionov, Oct 05 '22 at 14:28
You should google `C# "?" operator`. That will lead you to the documentation, or at the very least the name to look up. — Logarr, Oct 05 '22 at 14:28
@DmitryBychenko You have that backwards. It will return `s1` if `b` is true. — Logarr, Oct 05 '22 at 14:29

frankM_DN · Accepted Answer · 2022-10-05T14:31:53.830

1

it's equivalent to

if (b)
{
     return s1;
}
else
{
     return s2;
}

Edit: As Alexey pointed out, I should clarify. return here isn't the return from your specific function it's just saying that the statement (b ? s1 : s2) will evaluate to either s1 or s2 based on the value of b.

Learn more here: https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/conditional-operator

edited Oct 05 '22 at 14:31

answered Oct 05 '22 at 14:28

frankM_DN

365
7

2

Note: `return` is not the calling function's `return` – Alexey S. Larionov Oct 05 '22 at 14:29

score 0 · Answer 2 · answered Oct 05 '22 at 16:07

It's comparing the strings represented by s1 and s2 and returns a string like "bar/foo" in the comparative order of the strings.

Note that string.Compare may have issues with casing and special characters, consider using string.CompareOrdinal instead.

C# what does (bool ? string : string) do?

2 Answers2