Delphi in a Nutshell

Name

SetLength Procedure

Syntax

procedure SetLength(var S: string; Length: Integer);
procedure SetLength(var A: Array type; Length: Integer);
procedure SetLength(var A: Array type; Len1: Integer; Len2...);

Description

The SetLength procedure changes the size of a string or dynamic array. If the new length is longer than the current length, the extra space is not initialized, unless the array contains strings, interfaces, other dynamic arrays, or Variants, in which case they are properly initialized.

SetLength is not a real procedure.

Tips and Tricks

• The Length is in logical units (array elements, characters). In particular, if S is a WideString, the Length is in characters, not bytes.

• If the string or array has multiple references, SetLength always creates a unique instance and sets its length, even if the new length is the same as the current length.

• If A is a multidimensional dynamic array, you can pass one or more lengths to SetLength. The first length is for the leftmost dimension, and subsequent lengths initialize successive dimensions. The default length is zero for any dimension that you omit from SetLength.

Example

// Return a string of length Length, filled with repetitions
// of the given character.
function FillString(Length: Integer; Fill: Char): string;
begin
  SetLength(Result, Length); FillChar(Result[1], Length, Fill); end; // Create a square identity matrix of size N. type TIntMatrix = array of array of integer; procedure SetIdentityMatrix(var M: TIntMatrix; N: Integer); ...