Difference between revisions of "Plus"
From Free Pascal wiki
Jump to navigationJump to search (put list of usage occurrences next to code examples) |
|||
| (3 intermediate revisions by the same user not shown) | |||
| Line 3: | Line 3: | ||
<div style="float:right; margin: 0 10px 10px 0; padding:40px; font-size:500%; font-family: Georgia; background-color: #f9f9f9; border: 2px solid #777777;">+</div> | <div style="float:right; margin: 0 10px 10px 0; padding:40px; font-size:500%; font-family: Georgia; background-color: #f9f9f9; border: 2px solid #777777;">+</div> | ||
| − | The symbol <syntaxhighlight lang="pascal" | + | The symbol <syntaxhighlight lang="pascal" inline>+</syntaxhighlight> (pronounced “plus”) is used to: |
* explicitly indicate the positive sign of a number, | * explicitly indicate the positive sign of a number, | ||
* add two numbers resulting to a number, | * add two numbers resulting to a number, | ||
* form a union of [[Set|sets]], | * form a union of [[Set|sets]], | ||
| − | * (FPC) concatenate two strings (or characters; except [[PChar|<syntaxhighlight lang="pascal" | + | * (FPC) concatenate two strings (or characters; except [[PChar|<syntaxhighlight lang="pascal" inline>pchar</syntaxhighlight>]]). |
| + | * if <syntaxhighlight lang="delphi" inline>{$modeSwitch arrayOperators+}</syntaxhighlight> (default in [[Mode Delphi|<syntaxhighlight lang="delphi" inline>{$mode Delphi}</syntaxhighlight>]]), concatenate arrays (since FPC 3.2.0) | ||
| + | * enable a feature in a <syntaxhighlight lang="delphi" inline>{$modeSwitch}</syntaxhighlight> | ||
<syntaxhighlight lang="pascal" line> | <syntaxhighlight lang="pascal" line> | ||
| Line 35: | Line 37: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
| − | In [[ASCII]], the character code decimal <syntaxhighlight lang="pascal" | + | The plus sign is also a unary operator. |
| + | One can write such stupid expressions as <syntaxhighlight lang="pascal" inline>++++++++++++++42</syntaxhighlight> which will evaluate to positive 42. | ||
| + | |||
| + | In [[ASCII]], the character code decimal <syntaxhighlight lang="pascal" inline>43</syntaxhighlight> (or [[Hexadecimal|hexadecimal]] <syntaxhighlight lang="pascal" inline>2B</syntaxhighlight>) is defined to be <syntaxhighlight lang="pascal" inline>+</syntaxhighlight> (plus sign). | ||
== see also == | == see also == | ||
| − | * {{Doc|package=RTL|unit=system|identifier=add|text=<syntaxhighlight lang="pascal" | + | * {{Doc|package=RTL|unit=system|identifier=.op-add-variant-ariant-ariant|text=<syntaxhighlight lang="pascal" inline>system.add</syntaxhighlight>}} |
| − | * {{Doc|package=RTL|unit=system|identifier=concat|text=<syntaxhighlight lang="pascal" | + | * {{Doc|package=RTL|unit=system|identifier=concat|text=<syntaxhighlight lang="pascal" inline>system.concat</syntaxhighlight>}} returns concatenation of strings |
| − | * {{Doc|package=RTL|unit=strings|identifier=strcat|text=<syntaxhighlight lang="pascal" | + | * {{Doc|package=RTL|unit=strings|identifier=strcat|text=<syntaxhighlight lang="pascal" inline>strings.strcat</syntaxhighlight>}} returns concatenation of [[PChar|<syntaxhighlight lang="pascal" inline>pchar</syntaxhighlight>]] strings |
{{Symbols}} | {{Symbols}} | ||
Latest revision as of 00:41, 17 October 2019
│
English (en) │
suomi (fi) │
français (fr) │
русский (ru) │
+
The symbol + (pronounced “plus”) is used to:
- explicitly indicate the positive sign of a number,
- add two numbers resulting to a number,
- form a union of sets,
- (FPC) concatenate two strings (or characters; except
pchar). - if
{$modeSwitch arrayOperators+}(default in{$mode Delphi}), concatenate arrays (since FPC 3.2.0) - enable a feature in a
{$modeSwitch}
1program plusDemo(input, output, stderr);
2
3var
4 x: longint;
5 g: set of (foo, bar);
6 m: string;
7begin
8 // unary operator: positive sign
9 x := +7; // x becomes positive 7
10 x := +$100; // x becomes 256
11 // (dollar sign denotes hexadecimal base)
12
13 // addition
14 x := 7 + 7; // x becomes 14
15 x := 7 + 7 + 7 + 7 + 7 + 7; // x becomes 42
16
17 // union of sets
18 g := [foo] + [bar]; // g becomes [foo, bar]
19
20 // concatenation of strings and/or characters (FPC/Delphi extension)
21 m := 'Hello ' + 'world!'; // m becomes 'Hello world!'
22end.
The plus sign is also a unary operator.
One can write such stupid expressions as ++++++++++++++42 which will evaluate to positive 42.
In ASCII, the character code decimal 43 (or hexadecimal 2B) is defined to be + (plus sign).
see also
system.addsystem.concatreturns concatenation of stringsstrings.strcatreturns concatenation ofpcharstrings
| single characters |
|
| character pairs |
|
