;
│
English (en) │
suomi (fi) │
français (fr) │
The semicolon ;
is used to
- conclude a declaration,
- conclude a constant,
resourceString
, ortype
definition, - separate formal parameters in a routine signature,
- separate a routine declaration from its attributes,
- terminate the program header,
- separate alternatives in variant records, and to
- separate statements, in contrast to other programming language where its purpose is to terminate a statement.
statement separator
necessity
Since language constructs only in their entirety constitute statements, semicolons may not split their components.
Most notably ;
cannot appear immediately before an else
that is part of an if … then
branch.
However, ;
in front of an end
usually is not necessary, but optional and it does not harm insert one anyway.
As a demonstration, that a single semicolon can make the difference, consider the following listings:
case c of
0: if false then c := 42;
else c := -1;
end;
If c
is zero, it remains zero, but becomes -1
otherwise.
case c of
0: if false then c := 42
else c := -1;
end;
Here, c
only becomes -1
if it has been zero before.
As a consequence, and general advice, always put everything in compound statements (i. e. embrace your statements by begin
and end
) where it is allowed, in order to mitigate such issues.
otherwise
(an Extended Pascal extension) instead of else
in case
-statements may prevent such mistakes.empty statement
In a sequence a semicolon without a preceding (qualified) statement indicates an empty statement.
Historically empty statements were used in conjunction with labels. Originally labels can only defined where a statement exists. If for instance a whole list of statements had to be bypassed, but no qualified statement followed thereafter, the empty statement still provided the possibility.
Also historically, case
-statements had to list all possible values the selector variable theoretically could have.
Now, if a value or range did not imply any action, yet had to be listed inside the case
-statement in order to fulfill this requirement, an empty statement is the shortest possible way to implement the situation.
other remarks
In the ASCII character set the semicolon takes the value 59
(hexadecimal $3B
).
single characters |
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character pairs |
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