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Clear

procedure Clear;

Example​

procedure ReuseBuffer(Buffer: TMemoryStream);
begin
  if Buffer = nil then Exit;

  Buffer.Clear;
  // Buffer.Size = 0 and Buffer.Position = 0.
end;

Usage​

Clear releases the memory allocation and resets the stream's logical Size and Position to zero while keeping the object reusable.

Additional Technical Info​

Clear discards all bytes, releases the allocated capacity, and sets both Size and Position to 0. The stream object remains valid and can grow again on a later write or SetSize call.

Any prior content becomes unavailable immediately. Clear is not a secure-memory erasure guarantee: the RTL releases/reallocates memory but does not promise that every byte is overwritten before the allocator can reuse it. Do not use this method alone as a secret-destruction control.

Clear affects only this memory stream. It does not free the stream object, other streams previously copied from/to it, or consumers holding the same reference. Those consumers observe the cleared state.

No I/O occurs and no cursor state is retained. Use Position assignment instead when the intention is only to reread existing bytes. Use SetSize(0) when capacity-retention behavior matters; current Clear explicitly sets capacity to zero whereas allocation strategy remains an implementation detail for resizing.

The example is source-reviewed only; no buffer was cleared.

External references

Created 2026-07-15