Operators - Revision history

Raffriff42: note comparison chaining

2017-11-16T14:27:36Z

note comparison chaining

Raffriff42: parentheses override normal precedence

2016-03-12T04:49:11Z

parentheses override normal precedence

Raffriff42: formatting, links, phrasing

2016-03-12T04:37:56Z

formatting, links, phrasing

Show changes

Raffriff42: vertical spacing

2015-12-05T17:11:46Z

vertical spacing

Raffriff42: add subcat's and TOC

2015-12-05T17:06:52Z

add subcat's and TOC

Reel.Deal: links

2015-02-16T21:50:37Z

links

Admin: 1 revision

2013-05-09T21:33:33Z

1 revision

Wilbert: not

2012-03-11T16:01:40Z

not

New page

As in all programming and scripting languages, operators in AviSynth script language allow the performance of actions (operations) onto [[Script_variables|variables]]. Operators form the basis for building up expressions, the building blocks of AviSynth scripts.

AviSynth operators follow loosely the same rules as C operators, regarding meaning, precedence and associativity. By loosely we mean that there are some exceptions, indicated in the text below.

Note that when a binary operator is applied to an int and a float, the int is first converted to float, as in C.

==== Available Operators per Type ====

For '''all types''' of operands (clip, int, float, string, bool) you can use the following operators:

{|border=1 cellspacing=2
| ==
| is equal
|-
| !=
| not equal
|-
| <>
| not equal (alternative to !=, v2.07)
|}

String comparisons are not case-sensitive, so "abc" == "ABC" returns ''true''.

For '''numeric''' types (int, float) you can use the following int/float-specific operators:

{|border=1 cellspacing=2
| +
| add
|-
| -
| subtract
|-
| *
| multiply
|-
| /
| divide
|-
| %
| mod
|-
| >=
| greater or equal than
|-
| <=
| less or equal than
|-
| <
| less than
|-
| >
| greater than
|}

''AviSynth in former versions parsed expressions from right to left, which gave unexpected results.'' For example:

* a = 10 - 5 - 5 resulted in 10 - (5 - 5) = 10 instead of (10 - 5) - 5 = 0 !
* b = 100. / 2. / 4. resulted in 100. / (2. / 4.) = 200 instead of (100. / 2.) / 4. = 12.5 !

These "bugs" have been corrected in v2.53!

For '''string''' type you can use the following string-specific operators:

{|border=1 cellspacing=2
| +
| concatenate
|-
| >=
| greater or equal than (v2.07)
|-
| <=
| less or equal than (v2.07)
|-
| <
| less than (v2.07)
|-
| >
| greater than (v2.07)
|}

Like the equality operator, these string comparisons are case-insensitive.

For '''clip''' type you can use the following clip-specific operators:

{|border=1 cellspacing=2
| +
| the same as the function [[Splice|UnalignedSplice]]
|-
| ++
| the same as the function [[Splice|AlignedSplice]]
|}

For '''bool''' type (true/false) you can use the following bool-specific operators:

{|border=1 cellspacing=2
| <nowiki>||</nowiki>
| or
|-
| &&
| and
|-
| ?:
| execute code conditionally
|-
| !
| not
|}

The conditional execution operator is used as in the following example:

b = (a==true) ? 1 : 2

This means in pseudo-basic:

if (a=true) then b=1 else b=2

From version v2.07, AviSynth provides a NOP() function which can be used inside a conditional execution block in cases where "else" may not otherwise be desirable (such as a conditional [[Import]] or LoadPlugin).

==== Operator Precedence ====

The precedence of AviSynth operators is presented at the table below. Operators higher to the top of the table have higher precedence. Operators inside the same row have the same order of precedence.

{|border=1 cellspacing=2
| *
| /
| %
|colspan=4|
|-
| +
| ++
| -
|colspan=4|
|-
| <
| >
| <=
| >=
| !=
| <>
| ==
|-
| &&
|colspan=6|
|-
| <nowiki>||</nowiki>
|colspan=6|
|-
| ?:
|colspan=6|
|}

The dot symbol ('''.'''), used in the "OOP notation" for a function call, is not strictly an operator, but effectively has a higher precedence than any operator symbol.
So for example, <code>a + b.f(args)</code> means <code>a + f(b, args)</code> and not <code>f(a+b, args)</code> (which could be written as <code>(a+b).f(args)</code>)
----
Back to [[AviSynth Syntax]].

[[Category:AviSynth_Syntax]]
[[Category:Scripting_Basics]]

← Older revision		Revision as of 14:27, 16 November 2017
Line 25:		Line 25:

	{{FuncArg\|string}} comparisons are not case-sensitive, so "abc" == "ABC" returns ''true''.		{{FuncArg\|string}} comparisons are not case-sensitive, so "abc" == "ABC" returns ''true''.
		+
		+	'''Note''' comparisons may be ''chained'':
		+	:<code>(3 <= x <= 5)</code> can be used where normally something like
		+	:<code>(3 <= x && x <= 5)</code> would be required.<sup>[http://forum.doom9.org/showthread.php?p=1783132#post1783132 (doom9)]

	==== For Numbers ====		==== For Numbers ====

@@ Line 181: / Line 181: @@
   a*function(b, c)
 </div>
-and not
+but since '''parentheses''' override normal precedence,
 <div {{BoxWidthIndent|20|2}} >
   function(a*b, c)
 </div>
 </div>

@@ Line 96: / Line 96: @@
   | the same as the function [[Splice|AlignedSplice]]
   |}
+<div style="height:0.7em"></div>
 ==== For Booleans ====

@@ Line 5: / Line 5: @@
 Note that when a binary operator is applied to an int and a float, the int is first converted to float, as in C.
-==== Available Operators per Type ====
+==== For All Variable Types ====
 For '''all types''' of operands (clip, int, float, string, bool) you can use the following operators:
@@ Line 21: / Line 21: @@
 String comparisons are not case-sensitive, so "abc" == "ABC" returns ''true''.
 For '''numeric''' types (int, float) you can use the following int/float-specific operators:
@@ Line 59: / Line 61: @@
 These "bugs" have been corrected in v2.53!
 For '''string''' type you can use the following string-specific operators:
@@ Line 80: / Line 84: @@
 Like the equality operator, these string comparisons are case-insensitive.
 For '''clip''' type you can use the following clip-specific operators:
@@ Line 90: / Line 96: @@
   | the same as the function [[Splice|AlignedSplice]]
   |}
 For '''bool''' type (true/false) you can use the following bool-specific operators:

@@ Line 115: / Line 115: @@
   if (a=true) then b=1 else b=2
-From version v2.07, AviSynth provides a NOP() function which can be used inside a conditional execution block in cases where "else" may not otherwise be desirable (such as a conditional [[Import]] or LoadPlugin).
+From version v2.07, AviSynth provides a [[Internal_functions#NOP|NOP()]] function which can be used inside a conditional execution block in cases where "else" may not otherwise be desirable (such as a conditional [[Import]] or [[Plugins|LoadPlugin]]).
 ==== Operator Precedence ====