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Capacity

property Capacity: Integer read write;

Example​

procedure ReserveEntries(const Items: TStringList; Minimum: Integer);
begin
  if Items.Capacity < Minimum then
    Items.Capacity := Minimum;
end;

Usage​

Gets or requests the list's allocated entry capacity without changing its logical Count.

  • Iterate only 0..Count-1; indexes up to Capacity are not valid entries.
  • Reserve only bounded, evidence-based sizes. Very large values can exhaust process memory.
  • Do not rely on a capacity request working for every TStrings string list.

Additional Technical Info​

Capacity is declared by hidden ancestor TStrings and is normally used through a concrete visible descendant such as TStringList. Capacity is storage headroom, not the number of valid entries.

Source-backed behaviour​

The base getter returns Count and the base setter does nothing, allowing descendants to opt out. TStringList overrides both: it reports allocated slots and resizes its backing managed array. A requested value below Count raises EStringListError; a larger value reserves storage but does not create entries.

Capacity can exceed Count and can change automatically as entries grow or when Clear releases storage. The exact growth strategy is an implementation detail.

Count is the logical size. Add grows storage when required and Clear can reset it.

Official RTL references​

Created 2026-07-15