View source for Internal functions/Boolean functions

== Boolean functions ==

These functions return true or false, if the condition that they test holds or not, respectively.

* {{ScriptFunction|IsBool||IsBool(var)}}
: Tests if ''var'' is of the bool type. ''var'' can be any expression allowed by the [[AviSynth Syntax]].
: ''Examples:''
 b = false
 IsBool(b) = true
 IsBool(1 < 2 && 0 == 1) = true
 IsBool(123) = false

* {{ScriptFunction|IsClip||IsClip(var)}}
: Tests if ''var'' is of the clip type. ''var'' can be any expression allowed by the [[AviSynth Syntax]].
: ''Examples:''
 c = [[AviSource]](...)
 IsClip(c) = true
 IsClip("c") = false

* {{ScriptFunction|IsFloat||IsFloat(var)}}
: Tests if ''var'' is of the float type. ''var'' can be any expression allowed by the [[AviSynth Syntax]].
: ''Examples:''
 f = [[Internal_functions/Numeric_functions|Sqrt]](2)
 IsFloat(f) = true
 IsFloat(2) = true   # ints are considered to be floats by this function
 IsFloat(true) = false

* {{ScriptFunction|IsInt||IsInt(var)}}
: Tests if ''var'' is of the int type. ''var'' can be any expression allowed by the [[AviSynth Syntax]].
: ''Examples:''
 IsInt(2) = true
 IsInt(2.1) = false
 IsInt(true) = false

* {{ScriptFunction|IsString||IsString(var)}}
: Tests if ''var'' is of the string type. ''var'' can be any expression allowed by the [[AviSynth Syntax]].
: ''Examples:''
 IsString("test") = true
 IsString(2.3) = false
 IsString([[Internal_functions/Conversion_functions|String]](2.3)) = true

* {{ScriptFunction|Exist|v2.07|Exist(filename)}}
: Tests if the file specified by ''filename'' exists.
: ''Examples:''
 filename = ...
 clp = Exist(filename) ? [[AviSource]](filename) : [[Internal_functions/Control_functions|Assert]](false, "file: " + filename + " does not exist")

* {{ScriptFunction|Defined||Defined(var)}}
: Tests if ''var'' is defined. Can be used inside [[Script_functions]] to test if an optional argument has been given an explicit value.
: More formally, the function returns false if its argument (normally a function argument or variable) has the void ('undefined') type, otherwise it returns true.
: ''Examples:''
 b_arg_supplied = Defined(arg)
 myvar = b_arg_supplied ? ... : ...

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Back to [[Internal functions]].

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