Difference between revisions of "Block"
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A '''block''' is a sequence of [[Declaration|declarations]] followed by a sequence of [[Statement|statements]]. | A '''block''' is a sequence of [[Declaration|declarations]] followed by a sequence of [[Statement|statements]]. | ||
The declarations are optional. | The declarations are optional. | ||
| − | The sequence of statements can be empty, but at least the [[Begin|<syntaxhighlight lang="pascal" enclose="none">begin</syntaxhighlight>]]…[[End|<syntaxhighlight lang="pascal" enclose="none">end</syntaxhighlight>]]-frame has to be present. | + | The sequence of statements can be empty, but at least the [[Begin|<syntaxhighlight lang="pascal" enclose="none">begin</syntaxhighlight>]]…[[End|<syntaxhighlight lang="pascal" enclose="none">end</syntaxhighlight>]]-frame has to be present (in [[Routine|routines]] [[Asm|<syntaxhighlight lang="pascal" enclose="none">asm</syntaxhighlight>]]…<syntaxhighlight lang="pascal" enclose="none">end</syntaxhighlight> is allowed, too). |
The key feature of a block is, that declarations are only valid while the statements are processed. | The key feature of a block is, that declarations are only valid while the statements are processed. | ||
This concept is known as [[Scope|scope]]. | This concept is known as [[Scope|scope]]. | ||
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end; | end; | ||
</syntaxhighlight> | </syntaxhighlight> | ||
| − | An indication, whether something constitutes a block, is, whether you can use as part of a routine definition, as well as make a [[Program|<syntaxhighlight lang="pascal" enclose="none">program</syntaxhighlight>]] out of it (syntactically; apart from the terminating dot). | + | An indication, whether something constitutes a block, is, whether you can use it as part of a routine definition, as well as make a [[Program|<syntaxhighlight lang="pascal" enclose="none">program</syntaxhighlight>]] out of it (syntactically; apart from the terminating dot). |
| + | |||
| + | == see also == | ||
| + | * [[Comments#block comments|block comments]] | ||
Revision as of 23:11, 29 November 2018
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A block is a sequence of declarations followed by a sequence of statements.
The declarations are optional.
The sequence of statements can be empty, but at least the begin…end-frame has to be present (in routines asm…end is allowed, too).
The key feature of a block is, that declarations are only valid while the statements are processed.
This concept is known as scope.
example
The following is a valid block:
const
foobar = -1;
type
booleanArray = array of boolean;
var
check: booleanArray;
begin
check := booleanArray.create(true, false, true);
end;
An indication, whether something constitutes a block, is, whether you can use it as part of a routine definition, as well as make a program out of it (syntactically; apart from the terminating dot).
