Reserved words

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The keywords of the individual compiler modes are summarized as follows:

Note: the terms keywords and reserved words are used interchangeably here is this correct?

To do: insert explanation/link to the online Free Pascal manual of what a keyword/reserved word is: e.g. can you name your variables "if" etc.

To do: create pages for the keywords if they don't exist yet (e.g. translate from the German version) and link to the online Free Pascal manual section on that keyword in those pages.

Reserved words in Turbo Pascal

The following keywords occur in Turbo Pascal mode:

keyword description
and Boolean operator requiring both conditions are true for the result to be true
array multiple elements with the same name
asm start of code written in assembly language
begin start of a block of code
break exit a case statemenr
case select a particular segement of code to execute based on a value
const declare an identifier with a fixed value, or a variable with an initialized value
constructor routine used to create an object
continue skips an iteration in a for-loop and restart execution at the beginning of the loop
destructor routine used to deallocate an object
div integer divide operator
do used to indicate start of a loop
downto used in a for loop to indicate the index variable is decremented
else used in if statement to provide an execution path when the if test fails
end end of a block of code, a record or certain other constructs]
false boolean value indicating a test failed; opposite of true. As of FPC 3.0.0. False is no longer a keyword.
file external data structure, typically stored on disc
for loop used to increment or decrement a control variable
function define start of a routine that returns a result value
goto used to exit a segment of code and jump to another point
if test a condition and perform a set of instructions based on the result
implementation define the internal routines in unit
in identifies elements in a collection
inline machine code inserted directly into a routine
interface public declarations of routines in a unit
label defines the target jump point for a goto
mod operator used to return the remainder of an integer division
nil pointer value indicating the pointer does not contain a value
not boolean operator that negates the result of a test
object defines an object construct
of defines the characteristics of a variable
operator defines a routine used to implement an operator
or boolean operator which allows either of two choices to be used
packed indicates the elements of an array are to use less space (this keyword is primarily for compatibility with older programs as packing of array elements is generally automatic)
procedure define start of a routine that does not return a result value
program defines start of an application. This keyword is usually optional.
record group a series of variables under a single name
repeat loop through a section of code through an until statement as long as the result of the test is true
set group a collection
shl operator to shift a value to the left; equivalent to multiplying by a power of 2
shr operator to shift a value to the right; equivalent to dividing by a power of 2
string declares a variable that contains multiple characters
then indicates start of code in an if test
to indicates a for variable is to be incremented
true boolean value indicating a test succeeded; opposite of false. As of FPC 3.0.0. True is no longer a keyword.
type declares kinds of records or new classes of variables
unit separately compiled module
until indicates end test of a repeat statement
uses names units this program or unit refers to
var declare variables
while test a value and if true, loop through a section of code
with reference the internal variables within a record without having to refer to the record itself
xor boolean operator used to invert an or test

Reserved words in Object Pascal

Object Pascal extends the (Turbo) Pascal language with both support for dealing more easily with objects (object orientation) as well as other newer/more advanced concepts (threads, etc).
In addition to the reserved words in Turbo Pascal, the following reserved words are available in Delphi mode as well:

finalization introduces an optional 'finalization' part of a unit.
finally part of a try - finally - end block
inherited calls functionb/procedure from ancestor class
initialization introduces an optional 'initialization' part of a unit.

Reserved words in Extended Free Pascal

The reserved words in Extended Free Pascal mode include:

Modifiers (directives)

The list below is a list of modifiers
Modifiers are not strictly reserved words; however they are used in the same way as reserved words.
See the Free Pascal manual for details.

abstract an abcstract class cannot be instantiated, only inherited
assembler assembler...end creates an assemby language block
cdecl C declaration mofifier
cppdecl C++ declaration mofifier
default For indexed properties to use them without specifying the property name
generic class creation modfifier
override overrriding of virtual functions
private private accessibility modifier, only class members can access data/functions/procedures
protected protected accessibility modifier, accessibility modifier, class members and inherited classes can access data/functions/procedures
public public accessibility modifier, public access to data/functions/procedures
published accessibility modifier, published properties are visible in IDE ar can be written to .lfm
read property read access
specialize specialization of generic classes
write property read access

Unsupported Turbo Pascal modifiers

The reason why these modifiers are not supported is that these modifiers deal with 16 bit code for DOS. In other words, these modifiers have special meaning for 16 bit programming under DOS and Windows 3.x.

As Free Pascal does not support 16 bit code (only 32 and 64 bit), these modifiers are irrelevant in Free Pascal code.


Note: However, these modifiers are supported in the DOS crosscompiler present in the FPC development version


More functionality

Apart from the language features provided by the reserved words/keywords mentioned above, there is a lot of functionality available for the programmer in the various libraries:

  • RTL: Run-Time Library, available for all FPC and Lazarus programs
  • FCL: Free Component Library: a core set of libraries available for Lazarus programs and usually for FPC (FPC can be compiled without it, but that only happens on purpose for low-memory embedded systems etc)
  • FPC Packages: other packages provided by FPC
  • Lazarus components: these are Lazarus components that can be dropped on a form and often based on FCL or FPC packages
  • Lazarus utility functions: e.g. the fileutil unit.

Apart from the libraries provided by FPC and Lazarus, there are more libraries/components available:

  • FPC user-supplied units: see the FPC wiki
  • Lazarus CCR: components
  • User-supplied code on the internet: see open source repositories like SourceForge and GitHub.