System.GetMemory Function

GetMemory allocates a memory block.

Pascal

function GetMemory(Size: Integer): Pointer; cdecl;

C++

__cdecl void * GetMemory(int Size);

File

System

Description

GetMemory allocates a block of the given Size on the heap, and returns the address of this memory. The bytes of the allocated buffer are not set to zero. To dispose of the buffer, use FreeMem. If there isn't enough memory available to allocate the block, an EOutOfMemory exception is raised.

Note: If the memory needs to be zero-initialized, use AllocMem instead.

Note: GetMemory is the C++ compatible version of GetMem.

C++ Examples:

Copy Code

/*
The following code demostrates the use of memory management functions in C++. Three
edit boxes and a button are expected onthe form.
*/
String __fastcall FastStrCat(String s1, String s2)
{
  /*
   Allocated enough space in FinalStr to copy the contents
   of the initial string + $00 character
  */
  wchar_t* finalStr = (wchar_t *)GetMemory((s1.Length() + 1) * sizeof(wchar_t));

  // Copy the contents of the first string
  MoveChars(s1.data(), finalStr, s1.Length() + 1);

  // And now expand the final string + $00 character
  finalStr = (wchar_t *)ReallocMemory(finalStr, (s1.Length() + s2.Length() + 1) * sizeof(wchar_t));

  // Copy the contents of the second string
  MoveChars(s2.data(), finalStr + s1.Length(), s2.Length() + 1);

  // Get the result in String
  String result = String(finalStr);
  FreeMemory(finalStr);

  return result;
}

void __fastcall TForm1::Button1Click(TObject *Sender)
{
  // Concatenate 2 string
  Edit3->Text = FastStrCat(Edit1->Text, Edit2->Text);
}

Delphi Examples:

Copy Code

{
This example requires a button, a test edit, and a populated
ClientDataSet.  Pipe the ClientDataSet through a DataSource
to a DGGrid or DBNavigator to control the current field.
Cast the data correctly according to the field type when
assigning to the test edit.
}

{$IFNDEF UNICODE}
uses SwSystem;
{$ENDIF}

procedure TForm1.Button1Click(Sender: TObject);
var MyBuffer: Pointer;
begin
{ Retrieve the "raw" data from Field1 }
with CDS.Fields[0] do
  begin
    if not IsBlob then { this does not work for BLOB fields }
    begin
      { Allocate space }
      MyBuffer:= GetMemory(DataSize);
      try
        if not GetData(MyBuffer) then
          MessageDlg(DisplayName + ' is NULL', mtInformation, [mbOK], 0)
        else
          { Do something with the data };
          Edit1.Text:= string(PAnsiChar(MyBuffer)); // for a stringfield
      finally
        { Free the space }
        FreeMem(MyBuffer, DataSize);
      end;
    end;
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
{$IFDEF UNICODE}
  CDS.LoadFromFile(GetCurrentDir + '\CDS.XML');
{$ELSE}
  CDS.LoadFromFile(gsAppPath + 'CDS.XML');
{$ENDIF}
end;