Difference between revisions of "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 [[Operator|operators]]. |
An operand may be | An operand may be | ||
* a literal value of any type, | * a literal value of any type, | ||
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== remarks == | == remarks == | ||
With [[Compiler directive|compiler directive]] | With [[Compiler directive|compiler directive]] | ||
| − | <syntaxhighlight lang="pascal" inline>{$extendedSyntax on}</syntaxhighlight> a function call as an expression can appear as a statement, too. | + | [[$extendedSyntax|<syntaxhighlight lang="pascal" inline>{$extendedSyntax on}</syntaxhighlight>]] a function call as an expression can appear as a [[statement]], too. |
This is useful if the function triggers side-effects, but the return value is not needed. | This is useful if the function triggers side-effects, but the return value is not needed. | ||
Latest revision as of 18:15, 25 January 2023
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English (en) │
suomi (fi) │
An expression is a non-productive rule that resolves by calculation into a value. They consist of at least one operand, and additional operands may be linked via non-unary operators. An operand may be
- a literal value of any type,
- a variable or constant referred to by its identifier, or
- a function call.
Examples of expressions are:
x + 5'Z'response<>42
Expressions, and parts thereof, can be classified by their result type. Usually primarily arithmetic and logic expressions are distinguished. An arithmetic expression results in a numeric value. A logic expression results in a Boolean value.
remarks
With compiler directive
{$extendedSyntax on} a function call as an expression can appear as a statement, too.
This is useful if the function triggers side-effects, but the return value is not needed.
see also
- article „expression“ in Wikipedia, the free online encyclopedia
- Tutorial: Boolean expressions
- Tutorial: How to use
tFPExpressionParser(if an expression entered by the user shall be interpreted)
