About GNU Pascal

The GNU Pascal Compiler (GPC) is, as the name says, the Pascal compiler of the GNU family. This means:

• 32/64 bit compiler,
• does not have limits like the 64 kB or 640 kB limit known from certain operating systems - even on those systems -,
• runs on all operating systems supported by GNU C, including
  • Linux on Intel, Alpha, and all other supported types of hardware,
  • the BSD family (FreeBSD, NetBSD, OpenBSD),
  • DOS with 32 bits (DJGPP and EMX),
  • MS-Windows 9x/NT (CygWin and mingw32),
  • OS/2 (EMX),
  • MIPS-SGI-IRIX,
  • Alpha-DEC-OSF,
  • Sparc-Sun-Solaris,
  • HP/UX
  and more,
• can act as a native or as a cross compiler between all supported systems,
• produces highly optimized code for all these systems,
• is Free Software (Open-Source Software) according to the GNU General Public License (see also GNU for remarks and translations),
• is compatible to other GNU languages and tools such as GNU C and the GNU debugger.

• ISO-7185 Standard Pascal,
• most of ISO-10206 Extended Pascal,
• Borland Pascal 7.0,
• parts of Pascal-SC (PXSC).

• From Standard Pascal: Many popular Pascal compilers claim to extend Standard Pascal but miss these important features.
  • Conformant array parameters - the standardized and comfortable way to pass arrays of varying size to procedures and functions. [Example]
  • Passing local procedures as procedural parameters - with full access to all variables of the "parent" procedure. [Example]
  • Automatic File Buffers and standard Get and Put procedures. Read ahead from files without temporary variables. [Example] This allows you, for instance, to validate numeric input from text files before reading without conversion through strings. [Example]
  • True packed records and arrays. Pack 8 Booleans into 1 byte. [Example]
  • Internal files. You don't have to worry about creating temporary file names and erasing the files later. [Example]
  • Global goto. (Yes, goto has its place when it is not restricted to stay in the current routine.) [Example]
  • Automatically set discriminants of variant records in New. [Example]
  • Sets of arbitrary size. [Example]
• From Extended Pascal:
  • Strings of arbitrary length. [Example]
  • ReadStr/WriteStr. Read from and write to strings with the full comfort of Readln/Writeln. [Example]
  • System-independent date/time routines. [Example]
  • Set member iteration:
    for Ch in [ 'A'..'Z', 'a'..'z' ] do ... [Example]
  • Complex numbers. [Example] [Example]
  • Initialized variables. [Example]
  • Functions can return array or record values.
  • Return value variables. [Example]
  • Modules.
  • Schemata - the Pascal way to get dynamic arrays without dirty tricks. [Example]
• Compatible to Borland Pascal 7.0 with objects (BP):
  • Supports units, objects, ... and makes even things like absolute variables portable. [Example]
  • Comes with portable versions of the BP standard units with full source.
  • True network-transparent CRT unit: You can run your CRT applications locally or while being logged in remotely, without any need to worry about different terminal types.
  • Fully functional GUI (X11) version of CRT (also completely network transparent).
  • The random function can produce the same sequence of pseudo-random numbers as BP does - if you need that instead of the much more elaborate default algorithm.
  • A Ports unit lets you access CPU I/O ports on systems where this makes sense. [Example]
• From Pascal-SC (PXSC):
  • User-definable operators. Add your vectors with "+".
• Carefully designed GNU extensions help you to make your real-world programs portable:
  • 64-bit signed and unsigned integer types.
  • A Delphi-compatible SetLength procedure for strings makes it unnecessary to use dirty tricks like assignments to the "zeroth character".
  • Special types guarantee compatibility to other GNU languages such as GNU C. Directives like (*$L foo.c *) make it easy to maintain projects written in multiple languages. [Example (Pascal part)] [Example (C part)]
  • Extensions like BitSizeOf and ConvertFromBigEndian help you to deal with different data sizes and endianesses.
  • Little somethings like DirSeparator, PathSeparator, GetTempDirectory help you to write programs that look and feel "at home" on all operating systems.
  • The PExecute routine lets you execute child processes in a portable way that takes full advantage of multitasking environments. [Example]
  • The GNU GetOpt routines give you comfortable access to Unix-style short and long command-line options with and without arguments. [Example]
  • Routines like FSplit or FSearch or FExpand know about the specifica of the various different operating systems.
• Useful and portable GNU standard units:
  • A pipe unit gives you inter-process communication even under plain DOS. [Example] [Demo process for the example]
  • With the GNU RegEx unit you can do searches with regular expressions. [Example]
  • The GNU MultiPrecision (GMP) unit allows you to do arithmetics with integer, real, and rational numbers of arbitrary precision. [Example: factorial] [Example: power] [Example: real power] [Example: pi]
  • Posix functions like ReadDir or StatFS provide an efficient, easy-to-use and portable interface to the operating system. [Example] [Example]
  • A DosUnix unit compensates for some of the incompatibilities between two families of operating systems. [Example]

• The GNU debugger (GDB) does not yet understand Pascal syntax and types; you have to use C syntax when debugging Pascal programs with GDB.
• With GPC you get longer compilation times than with e.g. Borland Pascal.

Get the most recent version!

The upcoming next version of GPC is in beta test stage. We already can recommend its use over that of gpc-2.0, the last official release. Just download it from ftp://agnes.dida.physik.uni-essen.de/gnu-pascal/beta/. We also recommend to join the GNU Pascal mailing list for up-to-date information and efficient support.

New features since version 2.0

We have significantly improved both the compatibility to Borland Pascal and to ISO-10206 Extended Pascal. For a detailed list of changes since version 2.0 see the GPC TODO list. Beware - there are lots of changes! ;-)

Co-workers welcome!

Able, committed programmers are always welcome in the GNU Pascal team. If you want to be independent of companies that you must pay for getting a compiler with more restrictive licensing conditions that only runs on one operating system, be invited to join the development team.

• About GNU Pascal
• Where to get it
• How to get support
• The GNU Pascal development team
• The GNU project
• Things still to do for GNU Pascal
• Miscellaneous

• Return to top page

Copyright (C) 1996-1999 Markus & Peter Gerwinski

This information is provided in the hope that it will be useful, but without any warranty. We disclaim any liability for the accuracy of this information.

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