Difference between revisions of "expression"
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| − | {{ | + | {{expression}} |
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An '''expression''' is a non-productive rule that resolves by calculation into a value. | An '''expression''' is a non-productive rule that resolves by calculation into a value. | ||
They consist of at least one operand, and additional operands may be linked via non-unary operators. | They consist of at least one operand, and additional operands may be linked via non-unary operators. | ||
An operand may be | An operand may be | ||
* a literal value of any type | * a literal value of any type | ||
| − | * a variable or constant identifier, or | + | * a [[Variable|variable]] or [[Constant|constant]] [[Identifier|identifier]], or |
| − | * a function call. | + | * a [[Function|function]] call. |
Examples of expressions are: | Examples of expressions are: | ||
* <syntaxhighlight lang="pascal" enclose="none">x + 5</syntaxhighlight> | * <syntaxhighlight lang="pascal" enclose="none">x + 5</syntaxhighlight> | ||
* <syntaxhighlight lang="pascal" enclose="none">'Z'</syntaxhighlight> | * <syntaxhighlight lang="pascal" enclose="none">'Z'</syntaxhighlight> | ||
| − | * <syntaxhighlight lang="pascal" enclose="none">response <> 42</syntaxhighlight> | + | * <syntaxhighlight lang="pascal" enclose="none">response</syntaxhighlight> [[Not_equal|<syntaxhighlight lang="pascal" enclose="none"><></syntaxhighlight>]] <syntaxhighlight lang="pascal" enclose="none">42</syntaxhighlight> |
Expressions, and parts thereof, can be classified by their result type. | Expressions, and parts thereof, can be classified by their result type. | ||
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== remarks == | == remarks == | ||
| − | With <syntaxhighlight lang="pascal" enclose="none">{$extendedSyntax on}</syntaxhighlight> a function call as an expression can appear as a statement, too. | + | With [[Compiler directive|compiler directive]] |
| + | <syntaxhighlight lang="pascal" enclose="none">{$extendedSyntax on}</syntaxhighlight> a function call as an expression can appear as a statement, too. | ||
== see also == | == see also == | ||
* [https://en.wikipedia.org/wiki/Expression_(computer_science) article „expression“] in Wikipedia, the free online encyclopedia | * [https://en.wikipedia.org/wiki/Expression_(computer_science) article „expression“] in Wikipedia, the free online encyclopedia | ||
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Revision as of 09:45, 19 April 2019
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An expression is a non-productive rule that resolves by calculation into a value. They consist of at least one operand, and additional operands may be linked via non-unary operators. An operand may be
- a literal value of any type
- a variable or constant identifier, or
- a function call.
Examples of expressions are:
x + 5'Z'response<>42
Expressions, and parts thereof, can be classified by their result type. Usually primarily arithmetic and logic expressions are distinguished. An arithmetic expression results in a numeric value. A logic expression results in a Boolean value.
remarks
With compiler directive
{$extendedSyntax on} a function call as an expression can appear as a statement, too.
see also
- article „expression“ in Wikipedia, the free online encyclopedia
