Using FreePascal (or Delphi if no FP examples), given a 2048 byte buffer that is as an "array of bytes", how can I search the buffer for "StringA"?
var
Buffer : array[1..2048] of byte;
...
repeat
i := 0;
BlockRead(SrcFile, Buffer, SizeOf(Buffer), NumRead);
// Now I want to search the buffer for "StringA"?
...
Thankyou
I think this will work in fpc without extra Unicode/AnsiString conversion :
function Find(const buf : array of byte; const s : AnsiString) : integer;
//returns the 0-based index of the start of the first occurrence of S
//or -1 if there is no occurrence
var
AnsiStr : AnsiString;
begin
SetString(AnsiStr, PAnsiChar(@buf[0]), Length(buf));
Result := Pos(s,AnsiStr) - 1; // fpc has AnsiString overload for Pos()
end;
Here's the naïve approach whereby we simply walk through the buffer byte by byte looking for the desired string.
function Find(const Buffer: array of Byte; const S: AnsiString): Integer;
//returns the 0-based index of the start of the first occurrence of S
//or -1 if there is no occurrence
var
N: Integer;
begin
N := Length(S);
if N>0 then
for Result := low(Buffer) to high(Buffer)-(N-1) do
if CompareMem(@Buffer[Result], Pointer(S), N) then
exit;
Result := -1;
end;
I don't use FPC but I expect that this will work unchanged and if not then I'm sure you can convert it.