&

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&

In ASCII the character code decimal 38 (or $26) is defined to be & (pronounced “ampersand”).

Pascal

octal base

In Pascal the & denotes an octal base number.

program messageNo(input, output, stderr);

uses
	baseUnix;

begin
	// withdraw group write access to current terminal
	// equivalent to invoking: mesg n
	fpChmod('/dev/stdin', &0600);
end.

In an octal base only the characters 0 through and including 7 are allowed. An optional sign is specified in front of the &.

As a passing remark, in a production program the number in the above example is better written as

fpChmod('/dev/stdin', S_IRUSR or S_IWUSR);

since it is more meaningful than having a raw number. Pascal is a high-level language. Use this advantage. Write what you mean, not what in fact the computer does.

  Note: Octal number literals are not supported in {$mode Delphi} and {$mode TP}.

identifier escape

FreePascal retroactively declared some new reserved words. In order of being capable of compiling old code with an up-to-date compiler version, which might fail due to those new reserved words, FPC declared the & as an escape character. Thus, without refactoring the code but escaping, i.e. prepending an & to the identifier, the compiler accepts the actual reserved word as a valid identifier. New code though shall come up with different identifier names, without utilizing this feature.

Lazarus

In Lazarus the & is used to

• indicate shortcut keys in TMenuItem