Mega Code Archive
A simple Like function
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Title: A simple Like function
Question: Is there a LIKE function in Delphi that compares a string with a pattern?
Answer:
Sometimes we need to know if a string matches a pattern, which is a
string with wildcards (for example '?' and '*'). Here we implement a
function that returns True if the string matches the pattern and
False if not.
function Like(AString, Pattern: string): boolean;
var
i, n, n1, n2: integer;
p1, p2: pchar;
label
match, nomatch;
begin
AString := UpperCase(AString);
Pattern := UpperCase(Pattern);
n1 := Length(AString);
n2 := Length(Pattern);
if n1 p1 := pchar(AString);
p2 := pchar(Pattern);
for i := 1 to n do begin
if p2^ = '*' then goto match;
if (p2^ '?') and (p2^ p1^) then goto nomatch;
inc(p1); inc(p2);
end;
if n1 n2 then begin
nomatch:
Result := False;
exit;
end else if n1 for i := n1 + 1 to n2 do begin
if not (p2^ in ['*','?']) then goto nomatch;
inc(p2);
end;
end;
match:
Result := True;
end;
Sample call
-----------
if Like('Walter', 'WA?T*') then
ShowMessage('It worked!');
If you want to see another example, we use this function to determine
if a file name matches a specification in the article "Determining if
a file name matches a specification" (keyword: MatchesSpec).
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