&: what changed
Revision 0 to 1. Removed lines have a minus sign; added lines have a plus sign.
Title: &
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| 1 | + | & | |
| 2 | + | ||
| 3 | + | In [[ASCII]] the character code decimal `38` (or [[Hexadecimal|$]]`26`) is defined to be `&` (pronounced “ampersand”). | |
| 4 | + | ||
| 5 | + | ## Pascal | |
| 6 | + | ||
| 7 | + | ### octal base | |
| 8 | + | ||
| 9 | + | In [[Pascal]] the `&` denotes an octal base number. | |
| 10 | + | ||
| 11 | + | ``` pascal | |
| 12 | + | program messageNo(input, output, stderr); | |
| 13 | + | ||
| 14 | + | uses | |
| 15 | + | baseUnix; | |
| 16 | + | ||
| 17 | + | begin | |
| 18 | + | // withdraw group write access to current terminal | |
| 19 | + | // equivalent to invoking: mesg n | |
| 20 | + | fpChmod('/dev/stdin', &0600); | |
| 21 | + | end. | |
| 22 | + | ``` | |
| 23 | + | ||
| 24 | + | In an octal base only the characters `0` through and including `7` are allowed. An optional sign is specified in front of the `&`. | |
| 25 | + | ||
| 26 | + | As a passing remark, in a production program the number in the above example is better written as | |
| 27 | + | ||
| 28 | + | ``` pascal | |
| 29 | + | fpChmod('/dev/stdin', S_IRUSR or S_IWUSR); | |
| 30 | + | ``` | |
| 31 | + | ||
| 32 | + | since it is more meaningful than having a raw number. Pascal is a high-level language. Use this advantage. Write what you *mean*, not what in fact the computer does. | |
| 33 | + | ||
| 34 | + | > **Note:** Octal number literals are not supported in [[Mode Delphi|{$mode Delphi}]] and [[Mode TP|{$mode TP}]]. | |
| 35 | + | ||
| 36 | + | ### identifier escape | |
| 37 | + | ||
| 38 | + | [[FPC|FreePascal]] retroactively declared some new [[Reserved word|reserved words]]. In order of being capable of compiling old code with an up-to-date [[Compiler|compiler]] version, which might fail due to those new reserved words, FPC declared the `&` as an escape character. Thus, without refactoring the code but escaping, i.e. prepending an `&` to the [[Identifier|identifier]], the compiler accepts the actual reserved word as a valid identifier. New code though shall come up with different identifier names, without utilizing this feature. | |
| 39 | + | ||
| 40 | + | ## Lazarus | |
| 41 | + | ||
| 42 | + | In [[Lazarus]] the `&` is used to | |
| 43 | + | ||
| 44 | + | - indicate shortcut keys in [[TMenuItem]] | |
| 45 | + | ||
| 46 | + | --- | |
| 47 | + | *From the Free Pascal wiki, page "&", as it stood on 2022-08-06 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).* |