Var: what changed
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Title: Var
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| 1 | + | The [[Keyword|keyword]] `var` is used to: | |
| 2 | + | ||
| 3 | + | - start section of [[Variable|variable]] declarations, and | |
| 4 | + | - declare a formal parameter as penetrating mutable. | |
| 5 | + | ||
| 6 | + | ## Variable declaration section | |
| 7 | + | ||
| 8 | + | In a [[Block|block]] the word `var` starts a section of one or more variable [[Declaration|declarations]]. | |
| 9 | + | ||
| 10 | + | ``` pascal | |
| 11 | + | var | |
| 12 | + | age: integer; | |
| 13 | + | ``` | |
| 14 | + | ||
| 15 | + | Variables bearing the same [[Type|data type]] can be grouped, by separating their respective [[Identifier|identifiers]] by a [[Comma|comma]]: | |
| 16 | + | ||
| 17 | + | ``` pascal | |
| 18 | + | var | |
| 19 | + | firstName, lastName, address: string; | |
| 20 | + | ``` | |
| 21 | + | ||
| 22 | + | ## Variable parameter | |
| 23 | + | ||
| 24 | + | The word `var` prior a formal parameter declaration indicates that this [[Variable parameter|parameter is variable]], that means assigning values to it will affect the named parameter at the call site. | |
| 25 | + | ||
| 26 | + | ``` pascal | |
| 27 | + | procedure censor(var xxx: longWord); | |
| 28 | + | begin | |
| 29 | + | if (xxx = $4655434B) or (xxx = $6675636B) then | |
| 30 | + | begin | |
| 31 | + | xxx := $2A2A2A2A; | |
| 32 | + | end; | |
| 33 | + | end; | |
| 34 | + | ``` | |
| 35 | + | ||
| 36 | + | After invoking `procedure censor` the value of the variable that was supplied at the call site (i. e. where the procedure was called) will (possibly) have changed, too. | |
| 37 | + | ||
| 38 | + | ## See also | |
| 39 | + | ||
| 40 | + | - [[Const|const]] | |
| 41 | + | ||
| 42 | + | --- | |
| 43 | + | *From the Free Pascal wiki, page "Var", as it stood on 2021-07-04 after a change by Kai Burghardt, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).* |