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1.5 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 a 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.

_________________________________________________________________________________________________________ Numbers
-- hex digit sequence -|hex digit--------------------------------------- -----------

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

-- bin digit sequence-- 1------------------------------------------- |- 0--|| -------|

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

-- ------ -------------------------------- unsigned integer - -digit sequence --| -$% -hebxin didgigitit seseqquuenecnece-|

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

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

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

-- -|-- ----------------------------------- unsigned number |-unusnigsingeneddinretaegler-|

-- signed number--|------unsigned number----------------------------- -sign--
___________________________________________________________________

Remark: It is to note that all decimal constants which do no fit within the -2147483648..2147483647 range, are silently and automatically parsed as real-type constants.

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