Format function

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The format function formats a series of values into a string. The format function is found in the unit SysUtils. For an in-depth explanation see the on line documentation.

Syntax

Format is overloaded with two ways to call it:

function Format( const Fmt: String; const Args: array of Const) : String;
function Format( const Fmt: String; const Args: array of Const; const FormatSettings: TFormatSettings) : String;

The Fmt String argument contains format specifiers or placeholders (e.g. %d) which correspond to and are replaced in the result string by values from the Args array. An array of const can hold a variable amount of values of different types, with the applicable types for the Format function being the variations of the Real, Integer, Pointer and String types. TFormatSettings is a record which holds information related to desired formatting of number, time, date and currency values.


The formatting rule for each given format specifier is:

% [ArgumentIndex] ['-'] [width] [. precision] ArgumentType
d Decimal (integer)
e Scientific
f Fixed
g General
m Money
n Number (floating)
p Pointer
s String
u Unsigned decimal
x Hexadecimal

Integer formatting

  %d Will print the integer as it is.
  %8d Will print the integer as it is. If the number of digits is less than 8, the output will be padded on the left.
  %-8d Will print the integer as it is. If the number of digits is less than 8, the output will be padded on the right.
  %.8d Will print the integer as it is. If the number of digits is less than 8, the output will be padded on the left with zeroes.

String formatting

  %s Will print the string as it is.
  %8s Will print the string as it is. If the string has less than 8 characters, the output will be space-padded on the left (right-justified).
  %-8s Will print the string as it is. If the string has less than 8 characters, the output will be space-padded on the right (left-justified).

Example to use

procedure TForm1.Button1Click(Sender: TObject);
var
  title,  title2,
  underline,
  line, row1, row2, row3,
  fmt : string;
  i : integer;
begin
  fmt := '%-12s';
  title := format(fmt,['Column 1']) + format(fmt,['Column 2']) ;
  for i := 1 to 12 do underline := underline + '-';
  underline := underline + underline ;
  fmt := '%-12d';
  line := format(fmt,[15]) + format(fmt,[8]) ;
  fmt := '%12s';
  title2 := format(fmt,['Column 1']) + format(fmt,['Column 2']) ;
  fmt := '%12d';
  row1 := format(fmt,[15]) + format(fmt,[8]) ;
  row2 := format(fmt,[1005]) + format(fmt,[809]) ;
  fmt := '%12.5d';
  row3 := format(fmt,[1005]) + format(fmt,[809]) ;
  Memo1.Lines.Add( title );
  Memo1.Lines.Add( underline );
  Memo1.Lines.Add( line );
  Memo1.Lines.Add( '' );
  Memo1.Lines.Add( title2 );
  Memo1.Lines.Add( underline );
  Memo1.Lines.Add( row1 );
  Memo1.Lines.Add( row2 );
  Memo1.Lines.Add( row3 );
end;

The above statements will create a set of strings that look like:

Column 1    Column 2    
------------------------
15          8           
    Column 1    Column 2
------------------------
          15           8
        1005         809
       01005       00809

See also