Title: Using case...of on Strings?
Question: How can you use case..of on a string?
Answer:
How can you use case..of on a string? Normally you cannot because it only allows ordinal types (numeric - char is numeric Ord() ).
I recently figured (though it isn't a new idea) to create some sort of numeric representation of the string.
My favoured way is CRC-32, though you could use any method AS LONG AS the turned number is unique.
I won't include the CRC-32 details here, just the ideology/theory.
Example:
procedure CompareStrings(S: String);
begin
case Crc32OfString(S) of
Crc32OfString('Hello'): // Do wotever...
Crc32OfString('Goodbye'): // Do wotever...
end;
end;
See it's as simple as that!
It isn't very efficent calling it like that, to optimize it you can HARD CODE the case..of values to speed up the process.
I orignally said mail me for the CRC-32 routine but because I've had a few people e-mail me showing interest you can download by whole CRC unit from:
http://www.workshell.co.uk/dev/delphi/crc.pas
As well as CRC-32, it offers similar routines for CRC-16, Adler32, Kermit16 and other hash routines.
I hope its useful to you...
Enjoy!