switch case question

Dar Scott dsc at swcp.com
Sat Nov 4 12:50:16 CST 2006


On Nov 4, 2006, at 10:56 AM, Tereza Snyder wrote:

>> That looked suspicious.  Sure enough, a number 6 will match a  
>> literal 6 in a case, but a string "6.0" will not match a literal 6  
>> in a case.  A string "6.0" will match a 6.0 case.  A number 6 will  
>> not match a 6.0 in the case.
>
>
> To be clear: these DO match in an if? or not?

Good question!

Yes.  If both values are the result of arithmetic or looks like a  
number (what I call numeral) including E notation and 0x notation,  
then a numerical comparison is done with 'is' and '='.  The 'if' uses  
that '=' operator, so that will work with numbers (numeral or the  
result of arithmetic).

The 'switch x' seems to convert x to a string and the 'case y' seems  
to convert y to a string, and then comparisons are made.  A numerical  
literal is a string in this case.  That is, it looks as though 'case  
5.0' is the same as 'case "5.0"'.

So, a 'switch' might not be equivalent to a similar 'if'.

The 'switch' does look at caseSensitive and does work with NUL  
characters (Rev null).

Is this interesting behavior of 'switch' a feature or a bug?  Or is  
this already in the docs?

Dar

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