How can I test that a value is within a range with a "case" statement instead of an "if" statement?

Question

Can the following if statement be converted to a case statement?

if (Number >= 5) and (Number <= 10) then
  lblAnswer.Caption := 'in range'
else
  lblAnswer.Caption := 'out of range';

My Answer :

Yes it can

case (number >= 5) and (Number <= 10) of
  lblAnswer.Caption := 'in range';
  lblAnswer.Caption := 'out of range';
end;

Is this correct?

Why do you want to do that? For such expressions, a `if ... then` is just the clearer and faster way of doing that. There is no interest in using a `case` here. — Arnaud Bouchez, Oct 18 '11 at 06:25
An alternate statement : if (number in [5..10]) then .. else .. — LU RD, Oct 18 '11 at 06:49
InRange() for when limits are not constant or out of set range. — David Heffernan, Oct 18 '11 at 07:29

score 26 · Answer 1 · answered Oct 18 '11 at 05:50

26

If Number has some integer data type, then:

case number of
5 .. 10: lblAnswer.Caption := 'in range';
else     lblAnswer.Caption := 'out of range';
end;

answered Oct 18 '11 at 05:50

da-soft

thx so i had to leave out the long code ... and just go to numbers alrite make sense now thx alot – user1000441 Oct 18 '11 at 05:51
4

Of course this will only work if number is an Integer and not a floating point type. – Uwe Raabe Oct 18 '11 at 05:58
1

@user1000441 if this answer solved your problem, you should mark it as "accepted answer" so others know your problem is solved. – HpTerm Jul 10 '14 at 08:29

user997287 · Answer 2 · 2011-10-18T06:07:39.213

8

A small correction:

case (number >= 5) and (Number <= 10) of
  true:lblAnswer.Caption := 'in range';
  false:lblAnswer.Caption := 'out of range';
end;

edited Oct 18 '11 at 06:07

answered Oct 18 '11 at 05:59

user997287

3

+1 This is the correct way of coding it using `case` but honestly there is no interest of using a `case` here instead of a `if .. then` statement. – Arnaud Bouchez Oct 18 '11 at 06:24
@peter, this code here is correct. But Arnaud means that an if then statement is more appropriate. – LU RD Oct 18 '11 at 06:44
1

Either da-soft's answer or an if statement. Very odd to write case with a boolean condition. I originally thought this was syntax error it looked so weird. This answer works but you'll never see it in anyone else's code. – David Heffernan Oct 18 '11 at 07:27
2

-1. I cannot endorse Boolean case statements. They can confuse the compiler, which in turn confuses the programmer. (For lengthy discussions on this topic, do a [newsgroup search for Boolean case statements](http://groups.google.com/groups/search?q=boolean+case+statement+kennedy), and include my name in the search terms.) – Rob Kennedy Oct 18 '11 at 15:18

score 1 · Answer 3 · edited Apr 10 '14 at 13:27

1

Function InRange (Lo,Hi,Val : Integer) : Boolean;
Begin
 Result := (Val>=Lo)And(Val<=Hi);
End;

edited Apr 10 '14 at 13:27

Jeroen

answered Apr 10 '14 at 12:47

Eli Fried

3 Answers3