System.ReallocMem Function

ReallocMem reallocates a memory block.

Pascal

procedure ReallocMem(var P: Pointer; Size: Integer);

C++

ReallocMem(void * P, int Size);

File

System

Description

GetMem allocates a block of the given Size on the heap. If you need to change the size of this memory block, call ReallocMem, passing the existing memory block pointer in P, and the revised block size in Size. If ReallocMem can't expand the memory block pointed to by P, it frees the referenced memory and copies the values to the newly allocated memory that is returned.

If there isn't enough memory available to extend the memory block to the desired size, an EOutOfMemory exception is raised.

Note: ReallocMemory is the C++ compatible version of ReallocMem.

Delphi Examples:

Copy Code

{
The following code demostrates the use of ReallocMem function. Three
edit boxes and a button are expected onthe form.
}
function FastStrCat(const S1, S2: String): String;
var
  FinalStr: PChar;
begin
  {
   Allocated enough space in FinalStr to copy the contents
   of the initial string + $00 character
  }
  GetMem(FinalStr, (Length(S1) + 1) * SizeOf(Char));

  { Copy the contents of the first string }
  MoveChars(S1[1], FinalStr^, Length(S1) + 1);

  { And now expand the final string + $00 character }
  ReallocMem(FinalStr, (Length(S1) + Length(S2) + 1) * SizeOf(Char));

  { Copy the contents of the second string }
  MoveChars(S2[1], FinalStr[Length(S1)], Length(S2) + 1);

  { Get the result in String }
  SetString(Result, FinalStr, Length(S1) + Length(S2));
  FreeMem(FinalStr);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  { Concatenate 2 string }
  Edit3.Text := FastStrCat(Edit1.Text, Edit2.Text);
end;