# AviSynth Syntax - Boolean functions

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

- 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

- 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

- IsFloat | | IsFloat(var)

Tests if var is of the float type. var can be any expression allowed by the AviSynth Syntax.

Examples:

    f = Sqrt(2)
    IsFloat(f) = true
    IsFloat(2) = true   # ints are considered to be floats by this function
    IsFloat(true) = false

- 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

- 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(String(2.3)) = true

- Exist | v2.07 | Exist(filename)

Tests if the file specified by filename exists.

Examples:

    filename = ...
    clp = Exist(filename) ? AviSource(filename) : Assert(false,
    "file: " + filename + " does not exist")

- 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 ? ... : ...

Back to Internal functions.

$Date: 2008/12/07 15:46:17 $