Plus

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+

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.add
• system.concat returns concatenation of strings
• strings.strcat returns concatenation of pchar strings