Functions for variables

Functions that check or change the values of variables (and can be used on attributes too).

cast

cast (value, type name)

hard-coded

Converts value to the named type and returns it. The type name can be quoted or bare - cast(x, "int") and cast(x, int) both work - and the useful ones are int, double, string and boolean.

cast (4.9, "int")
-> 4
cast (7, "double")
-> 7 (as a double)

Converting to int truncates towards zero rather than rounding, so cast(4.9, "int") is 4 and cast(-4.9, "int") is -4.

This is the way to turn a double into an integer, since ToInt only accepts strings - see Values and types. It is most often needed after Floor, Ceiling, Round or Truncate, which return a whole number but as a double.

cast is not a library function and is not implemented in C# alongside the other hard-coded functions either; it is handled directly by the expression evaluator, which is why you will not find it in the editor’s function list. It exists for compatibility with expressions written for older versions of Quest.

Equal

Equal (value, value)

Returns a boolean - true if the two values are the same, false otherwise. Generally this can be accomplished more easily using the equals sign, but if you try to compare two things that might be different types, this is the safer way, as it first compares the types, and only if they match does it compare the values (trying to compare an int with null, for example, will generate an error).

This does mean you can test an attribute that might not exist in one step instead of two. Instead of this:

if (HasInt(object, "status")) {
  if (object.status = 1) {
    msg("This has been done.")
  }
  else {
    msg ("Not done yet.")
  }
}
else {
  msg ("Not done yet.")
}

You can do:

if (Equal(object.status, 1)) {
  msg("This has been done.")
}
else {
  msg ("Not done yet.")
}

if

if (boolean condition, value if true, value if false)

hard-coded

Returns one of two values depending on the condition. This is the expression form - for the if script command, which runs one of two scripts, see the script commands page.

msg ("The lamp is " + if (lamp.switchedon, "on", "off") + ".")

Only the branch that is taken is evaluated, so the other one is safe to write even if it would fail.

Like cast, this is handled by the expression evaluator rather than being a library or C# function, so it does not appear in the editor’s function list.

IsDefined

IsDefined (string variable name)

hard-coded

Returns a boolean indicating whether the specified variable name is defined in the current scope.

IsDouble

IsDouble (string number)

hard-coded

Returns a boolean indicating whether the specified string represents a double.

IsInt

IsInt (string number)

hard-coded

Returns a boolean indicating whether the specified string represents an integer.

ToDouble

ToDouble (string number)

hard-coded

Returns a double - converts a valid string to a double.

Note: An error occurs if the string does not represent a number. As with ToInt, this only takes a string - passing an int stops with an error, so use cast to convert one.

ToInt

ToInt (string number)

hard-coded

Returns an int - converts a valid string to an integer.

Note: An error occurs if the string does not represent a number. Use IsInt to test if a string represents a number first.

ToInt only takes a string. Passing a double stops with “ToInt function does not handle parameters of types Double” - use cast for that.

ToString

ToString (anything)

hard-coded

Returns a string. This is most useful for converting an integer or double to a string, however it will also convert an object, script, list or dictionary to a string, prefixing the string with the type (eg, “Object: player” or “List: one; two; three; “). It will even convert a string to exactly the same string!

TypeOf

TypeOf (object, string attribute name)

hard-coded

Returns a string representing the name of the type of the specified object’s attribute.

TypeOf (value)

Returns a string representing the name of the type of the specified value.

See Attribute Types for a list of strings that may be returned.