Delphi 6: How to search a dynamic array for sub-string quickly?

Question

How can I search a dynamic array of char in Delphi 6 for a sub-string and get back an index to a match, not a pointer? I've seen functions in Delphi 6 that do this for strings but not for dynamic char arrays. There is a function called SearchBuf but that function returns a PChar pointer to the match location when what I need is the array index of the match.

Thanks.

Any particular reason you're using a dynamic array of characters? I can't think of a single advantage they offer over strings. — Rob Kennedy
– Rob Kennedy, Commented May 30, 2010 at 4:32
I am moving data in out between functions that manage audio data in char array format. It's a legacy code thing. — Robert Oschler
– Robert Oschler, Commented Jun 4, 2010 at 1:32
If you set the length of a string variable to the size of your dynamic array, then you can type-cast that string to PChar and you'll have an equally good character array for the function to read or fill. — Rob Kennedy
– Rob Kennedy, Commented Jun 4, 2010 at 3:04

Rob Kennedy · Accepted Answer · 2010-05-30 04:30:26Z

1

If you have a pointer to the match, simply subtract the pointer to the first character, and you'll have your index.

var
  Buf, Result: PChar;
  Index: Integer;

Result := SearchBuf(Buf, ...);
if Assigned(Result) then
  Index := Result - Buf
else
  Index := -1; // not found

I'm pretty sure that pointer arithmetic is allowed in Delphi 6. If not, then type-cast the pointers to integral types first:

Index := Cardinal(Result) - Cardinal(Buf);

answered May 30, 2010 at 4:30

Rob Kennedy

164k23 gold badges288 silver badges481 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Delphi 6: How to search a dynamic array for sub-string quickly?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related