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1.6 Numbers

Numbers are by default denoted in decimal notation. Real (or decimal) numbers are written using engineering or scientific notation (e.g. 0.314E1).

For integer type constants, Free Pascal supports 4 formats:

  1. Normal, decimal format (base 10). This is the standard format.
  2. Hexadecimal format (base 16), in the same way as Turbo Pascal does. To specify a constant value in hexadecimal format, prepend it with a dollar sign ($). Thus, the hexadecimal $FF equals 255 decimal. Note that case is insignificant when using hexadecimal constants.
  3. As of version 1.0.7, Octal format (base 8) is also supported. To specify a constant in octal format, prepend it with an ampersand (&). For instance 15 is specified in octal notation as &17.
  4. Binary notation (base 2). A binary number can be specified by preceding it with a percent sign (%). Thus, 255 can be specified in binary notation as %11111111.

The following diagrams show the syntax for numbers.

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Numbers

--hex digit sequence|hex digit-------------------------------------- ----------

--octal digit sequence-octal digit------------------------------------ ----------|

-- ---- ------------------------------------------- bin digit sequence |-10 -|| ------|

-- --- -------------------------------------------- digit sequence -digit-|

--unsigned integer|----digit sequence------------------------------- |-$ -hex digit sequence--| |-& -octal digit sequence| % bin digit sequence

--sign|+ -------------------------------------------------------- -----

--unsigned real digit sequence -|-----------------|------------------- -.-digit sequence- -scale factor--

--scale factor-|E ---|------digit sequence--------------------------- -e -- -sign--

--unsigned number---unsigned real---------------------------------- -unsigned integer-|

-- --------- ---------------------------- signed number - -| unsigned number sign
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Remark: Octal and Binary notation are not supported in TP or Delphi compatibility mode.

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