Difference between revisions of "expression"
From Free Pascal wiki
Jump to navigationJump to searchm (insert link to Operator) |
|||
Line 2: | Line 2: | ||
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, |
Revision as of 06:27, 27 June 2020
│
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)