Variables and Expressions

Dereference or name substitution.

When Expr evaluates to a VarRef, %Expr% accesses the corresponding variable. For example, x := &y takes a reference to y and assigns it to x, then %x% := 1 assigns to the variable y and %x% reads its value.

Otherwise, the value of the sub-expression Expr is used as the name or partial name of a variable or property. This allows the script to refer to a variable or property whose name is determined by evaluating Expr, which is typically another variable. Variables cannot be created dynamically, but a variable can be assigned dynamically if it has been declared or referenced non-dynamically somewhere in the script.

Note: The result of the sub-expression Expr must be the name or partial name of the variable or property to be accessed.

Percent signs cannot be used directly within Expr due to ambiguity, but can be nested within parentheses. Otherwise, Expr can be any expression.

If there are any adjoining %Expr% sequences and partial names (without any spaces or other characters between them), they are combined to form a single name.

An Error is typically thrown if the variable does not already exist, or if it is uninitialized and its value is being read. The or-maybe operator (??) can be used to avoid that case by providing a default value. For example: %'novar'% ?? 42.

Although this is historically known as a "double-deref", this term is inaccurate when Expr does not contain a variable (first deref), and also when the resulting variable is the target of an assignment, not being dereferenced (second deref).

Maybe. Permits the variable to be unset. This is valid only when passing a variable to an optional parameter, array element or object literal; or on the right-hand side of a direct assignment. The question mark must be followed by one of the following symbols (ignoring whitespace): )]},:. The variable may be passed conditionally via the ternary operator or on the right-hand side of AND/OR.

The variable is typically an optional parameter, but can be any variable. For variables that are not function parameters, a VarUnset warning may still be shown at load-time if there are other references to the variable but no assignments.

This operator is currently supported only for variables. To explicitly or conditionally omit a parameter in more general cases, use the unset keyword.

See also: unset (Optional Parameters)

Pre- and post-increment/decrement. Adds or subtracts 1 from a variable. The operator may appear either before or after the variable's name. If it appears before the name, the operation is performed and its result is used by the next operation (the result is a variable reference in this case). For example, Var := ++X increments X and then assigns its value to Var. Conversely, if the operator appears after the variable's name, the result is the value of X prior to performing the operation. For example, Var := X++ increments X but Var receives the value X had before it was incremented.

These operators can also be used with a property of an object, such as myArray.Length++ or --myArray[i]. In these cases, the result of the sub-expression is always a number, not a variable reference.

Power. Example usage: Base**Exponent. Both Base and Exponent may contain a decimal point. If Exponent is negative, the result will be formatted as a floating point number even if Base and Exponent are both integers. Since ** is of higher precedence than unary minus, -2**2 is evaluated like -(2**2) and so yields -4. Thus, to raise a literal negative number to a power, enclose it in parentheses such as (-2)**2.

The power operator is right-associative. For example, x ** y ** z is evaluated as x ** (y ** z).

Note: A negative Base combined with a fractional Exponent such as (-2)**0.5 is not supported; attempting it will cause an exception to be thrown. But both (-2)**2 and (-2)**2.0 are supported. If both Base and Exponent are 0, the result is undefined and an exception is thrown.

Unary minus (-): Inverts the sign of its operand.

Unary plus (+): +N is equivalent to -(-N). This has no effect when applied to a pure number, but can be used to convert numeric strings to pure numbers.

Logical-not (!): If the operand is blank or 0, the result of applying logical-not is 1, which means "true". Otherwise, the result is 0 (false). For example: !x or !(y and z). Note: The word NOT is synonymous with ! except that ! has a higher precedence. Consecutive unary operators such as !!Var are allowed because they are evaluated in right-to-left order.

Bitwise-not (~): This inverts each bit of its operand. As 64-bit signed integers are used, a positive input value will always give a negative result and vice versa. For example, ~0xf0f evaluates to -0xf10 (-3856), which is binary equivalent to 0xfffffffffffff0f0. If an unsigned 32-bit value is intended, the result can be truncated with result & 0xffffffff. If the operand is a floating point value, a TypeError is thrown.

Reference (&): Creates a VarRef, which is a value representing a reference to a variable. A VarRef can then be used to indirectly access the target variable. For example, ref := &target followed by %ref% := 1 would assign the value 1 to target. The VarRef would typically be passed to a function, but could be stored in an array or property. See also: Dereference, ByRef.

Taking a reference to a built-in variable such as A_Clipboard is currently not supported, except when being passed directly to an OutputVar parameter of a built-in function.

Multiply (*): The result is an integer if both inputs are integers; otherwise, it is a floating point number.

Other uses: The asterisk (*) symbol is also used in variadic function calls.

True divide (/): True division yields a floating point result even when both inputs are integers. For example, 3/2 yields 1.5 rather than 1, and 4/2 yields 2.0 rather than 2.

Integer divide (//): The double-slash operator uses high-performance integer division. For example, 5//3 is 1 and 5//-3 is -1. If either of the inputs is in floating point format, a TypeError is thrown. For modulo, see Mod.

The *= and /= operators are a shorthand way to multiply or divide the value in a variable by another value. For example, Var*=2 produces the same result as Var:=Var*2 (though the former performs better).

Division by zero causes a ZeroDivisionError to be thrown.

Add (+) and subtract (-). On a related note, the += and -= operators are a shorthand way to increment or decrement a variable. For example, Var+=2 produces the same result as Var:=Var+2 (though the former performs better). Similarly, a variable can be increased or decreased by 1 by using Var++, Var--, ++Var, or --Var.

Other uses: If the + or - symbol is not preceded by a value (or a sub-expression which yields a value), it is interpreted as a unary operator instead.

Bit shift left (<<). Example usage: Value1 << Value2. This is equivalent to multiplying Value1 by "2 to the Value2th power".

Arithmetic bit shift right (>>). Example usage: Value1 >> Value2. This is equivalent to dividing Value1 by "2 to the Value2th power" and rounding the result to the nearest integer leftward on the number line; for example, -3>>1 is -2.

Logical bit shift right (>>>). Example usage: Value1 >>> Value2. Unlike arithmetic bit shift right, this does not preserve the sign of the number. For example, -1 has the same bit representation as the unsigned 64-bit integer 0xffffffffffffffff, therefore -1 >>> 1 is 0x7fffffffffffffff.

The following applies to all three operators:

• If either of the inputs is a floating-point number, a TypeError is thrown.
• A 64-bit operation is performed and the result is a 64-bit signed integer.
• If Value2 is less than 0 or greater than 63, an exception is thrown.

Bitwise-and (&), bitwise-exclusive-or (^), and bitwise-or (|). Of the three, & has the highest precedence and | has the lowest.

The following applies to all three operators:

• If either of the inputs is a floating-point number, a TypeError is thrown.
• A 64-bit operation is performed and the result is a 64-bit signed integer.

Related: Bitwise-not (~)

Concatenate. A period (dot) with at least one space or tab on each side is used to combine two items into a single string. You may also omit the period to achieve the same result (except where ambiguous such as x -y, or when the item on the right side has a leading ++ or --). When the dot is omitted, there must be at least one space or tab between the items to be merged.

Var := "The color is " . FoundColor  ; Explicit concat
Var := "The color is " FoundColor    ; Auto-concat

Sub-expressions can also be concatenated. For example: Var := "The net price is " . Price * (1 - Discount/100).

A line that begins with a period (or any other operator) is automatically appended to the line above it.

The entire length of each input is used, even if it includes binary zero. For example, Chr(0x2010) Chr(0x0000) Chr(0x4030) produces the following string of bytes (due to UTF-16-LE encoding): 0x10, 0x20, 0, 0, 0x30, 0x40. The result has an additional null-terminator (binary zero) which is not included in the length.

Other uses: If there is no space or tab to the right of a period (dot), it is interpreted as either a literal floating-point number or member access. For example, 1.1 and (.5) are numbers, A_Args.Has(3) is a method call and A_Args.Length is a property access.

Greater (>), less (<), greater-or-equal (>=), and less-or-equal (<=). The inputs are compared numerically. A TypeError is thrown if either of the inputs is not a number or a numeric string.

Case-insensitive equal (=) / not-equal (!=) and case-sensitive equal (==) / not-equal (!==). The == operator behaves identically to = except when either of the inputs is not numeric (or both are strings), in which case == is always case-sensitive and = is always case-insensitive. The != and !== behave identically to their counterparts without !, except that the result is inverted.

The == and !== operators can be used to compare strings which contain binary zero. All other comparison operators except ~= compare only up to the first binary zero.

For case-insensitive comparisons, only the ASCII letters A-Z are considered equivalent to their lowercase counterparts. To instead compare according to the rules of the current user's locale, use StrCompare and specify "Locale" for the CaseSense parameter.

Value is Class yields 1 (true) if Value is an instance of Class, otherwise 0 (false). Class must be an Object with an own Prototype property, but typically the property is defined implicitly by a class definition. This operation is generally equivalent to HasBase(Value, Class.Prototype).

in and contains are reserved for future use.

Both of these are logical-AND. For example: x > 3 and x < 10.

In an expression where all operands are true, the last operand is returned. Otherwise, the first operand that is false is returned. In other words, the result is true only if all operands are true. Boolean expressions are subject to short-circuit evaluation (from left to right) to improve performance.

In the following example, all operands are true and will be evaluated:

A := 1, B := {}, C := 20, D := true, E := "str"
MsgBox(A && B && C && D && E) ; Shows "str" (E).

In the following example, only the first two operands will be evaluated because B is false. The rest is ignored, i.e. C is not incremented either:

A := 1, B := "", C := 0, D := false, E := "str"
MsgBox(A && B && ++C && D && E) ; Shows "" (B).

A line that begins with AND or && (or any other operator) is automatically appended to the line above it.

Both of these are logical-OR. For example: x <= 3 or x >= 10.

In an expression where at least one operand is true, the first operand that is true is returned. Otherwise, the last operand that is false is returned. In other words, if at least one operand is true, the result is true. Boolean expressions are subject to short-circuit evaluation (from left to right) to improve performance.

In the following example, at least one operand is true. All operands up to D will be evaluated. E is ignored and will never be incremented:

A := "", B := false, C := 0, D := "str", E := 20
MsgBox(A || B || C || D || ++E) ; Shows "str" (D).

In the following example, all operands are false and will be evaluated:

A := "", B := false, C := 0
MsgBox(A || B || C) ; Shows "0" (C).

A line that begins with OR or || (or any other operator) is automatically appended to the line above it.

Or maybe, otherwise known as the coalescing operator. If the left operand (which must be a variable) has a value, it becomes the result and the right branch is skipped. Otherwise, the right operand becomes the result. In other words, A ?? B behaves like A || B (logical-OR) except that the condition is IsSet(A).

This is typically used to provide a default value when it is known that a variable or optional parameter might not already have a value. For example:

MsgBox MyVar ?? "Default value"

Since the variable is expected to sometimes be uninitialized, no error is thrown in that case. Unlike IsSet(A) ? A : B, a VarUnset warning may still be shown at load-time if there are other references to the variable but no assignments.

Ternary operator. This operator is a shorthand replacement for the if-else statement. It evaluates the condition on its left side to determine which of its two branches should become its final result. For example, var := x>y ? 2 : 3 stores 2 in Var if x is greater than y; otherwise it stores 3. To enhance performance, only the winning branch is evaluated (see short-circuit evaluation).

See also: maybe (var?), or-maybe (??)

Note: When used at the beginning of a line, the ternary condition should usually be enclosed in parentheses to reduce ambiguity with other types of statements. For details, see Expression Statements.

Assign. Performs an operation on the contents of a variable and stores the result back in the same variable. The simplest assignment operator is colon-equal (:=), which stores the result of an expression in a variable. For a description of what the other operators do, see their related entries in this table. For example, Var //= 2 performs integer division to divide Var by 2, then stores the result back in Var. Similarly, Var .= "abc" is a shorthand way of writing Var := Var . "abc".

Unlike most other operators, assignments are evaluated from right to left. Consequently, a line such as Var1 := Var2 := 0 first assigns 0 to Var2 then assigns Var2 to Var1.

If an assignment is used as the input for some other operator, its value is the variable itself. For example, the expression (Var+=2) > 50 is true if the newly-increased value in Var is greater than 50. It is also valid to combine an assignment with the reference operator, as in &(Var := "initial value").

The precedence of the assignment operators is automatically raised when it would avoid a syntax error or provide more intuitive behavior. For example: not x:=y is evaluated as not (x:=y). Also, x==y && z:=1 is evaluated as x==y && (z:=1), which short-circuits when x doesn't equal y. Similarly, ++Var := X is evaluated as ++(Var := X); and Z>0 ? X:=2 : Y:=2 is evaluated as Z>0 ? (X:=2) : (Y:=2).

The target variable can be un-set by combining a direct assignment (:=) with the unset keyword or the maybe (var?) operator. For example: Var := unset, Var1 := (Var2?).

An assignment can also target a property of an object, such as myArray.Length += n or myArray[i] .= t. When assigning to a property, the result of the sub-expression is the value being assigned, not a variable reference.

Fat arrow function. Defines a simple function and returns a Func or Closure object. Write the function's parameter list (optionally preceded by a function name) to the left of the operator. When the function is called (via the returned reference), it evaluates the sub-expression expr and returns the result.

The following two examples are equivalent:

sumfn := Sum(a, b) => a + b

Sum(a, b) {
    return a + b
}
sumfn := Sum

In both cases, the function is defined unconditionally at the moment the script launches, but the function reference is stored in sumfn only if and when the assignment is evaluated.

If the function name is omitted and the parameter list consists of only a single parameter name, the parentheses can be omitted. The example below defines an anonymous function with one parameter a and stores its reference in the variable double:

double := a => a * 2

Variable references in expr are resolved in the same way as in the equivalent full function definition. For instance, expr may refer to an outer function's local variables (as in any nested function), in which case a new closure is created and returned each time the fat arrow expression is evaluated. The function is always assume-local, since declarations cannot be used.

Specifying a name for the function allows it to be called recursively or by other nested functions without storing a reference to the closure within itself (thereby creating a problematic circular reference). It can also be helpful for debugging, such as with Func.Name or when displayed on the debugger's call stack.

Fat arrow syntax can also be used to define shorthand properties and methods.

Comma (multi-statement). Commas may be used to write multiple sub-expressions on a single line. This is most commonly used to group together multiple assignments or function calls. For example: x:=1, y+=2, ++index, MyFunc(). Such statements are executed in order from left to right.

Note: A line that begins with a comma (or any other operator) is automatically appended to the line above it.

Comma is also used to delimit the parameters of a function call or control flow statement. To include a multi-statement expression in a parameter list, enclose it in an extra set of parentheses. For example, MyFn((x, y)) evaluates both x and y but passes y as the first and only parameter of MyFn.

Any sub-expression enclosed in parentheses. For example, (3 + 2) * 2 forces 3 + 2 to be evaluated first.

For a multi-statement expression, the result of the last statement is returned. For example, (a := 1, b := 2, c := 3) returns 3.

Function call. There must be no space between the function name or expression and the open parenthesis which begins the parameter list. For details, see Function Calls.

(expression) is not necessarily required to be enclosed in parentheses, but doing so may eliminate ambiguity. For example, (x.y)() retrieves a function from a property and then calls it with no parameters, whereas x.y() would implicitly pass x as the first parameter.

Variadic function call. Params is an enumerable object (an object with an __Enum method), such as an Array containing parameter values.

Item access. Get or set the __Item property (or default property) of object x with the parameter y (or multiple parameters in place of y). This typically corresponds to an array element or item within a collection, where y is the item's index or key. The item can be assigned a value by using any assignment operator immediately after the closing bracket. For example, x[y] := z.

Array literal. If the open-bracket is not preceded by a value (or a sub-expression which yields a value), it is interpreted as the beginning of an array literal. For example, [a, b, c] is equivalent to Array(a, b, c) (a, b and c are variables).

See Arrays and Maps for common usage.

Object literal. Create an Object. Each pair consists of a literal property name a and a property value expression b. For example, x := {a: b} is equivalent to x := Object(), x.a := b. Base may be set within the object literal, but all other properties are set as own value properties, potentially overriding properties inherited from the base object.

To use a dynamic property name, enclose the sub-expression in percent signs. For example: {%nameVar%: valueVar}.

Can be used to get or set the script's current working directory, which is where files will be accessed by default. The final backslash is not included unless it is the root directory. Two examples: C:\ and C:\My Documents.

SetWorkingDir can also be used to change the working directory.

The script's working directory defaults to A_ScriptDir, regardless of how the script was launched.

The full path of the directory where the current script is located. The final backslash is omitted (even for root directories).

If the script text is read from stdin rather than from file, this variable contains the initial working directory.

Can be used to get or set the default title for MsgBox, InputBox, FileSelect, DirSelect and Gui. If not set by the script, it defaults to the file name of the current script, without its path, e.g. MyScript.ahk.

If the script text is read from stdin rather than from file, this variable contains an asterisk (*).

If the script is compiled or embedded, this is the name of the current executable file.

The full path of the current script, e.g. C:\Scripts\My Script.ahk

If the script text is read from stdin rather than from file, this variable contains an asterisk (*).

If the script is compiled or embedded, this is the full path of the current executable file.

The number of the currently executing line within the script (or one of its #Include files). This line number will match the one shown by ListLines; it can be useful for error reporting such as this example: MsgBox "Could not write to log file (line number " A_LineNumber ")".

Since a compiled script has merged all its #Include files into one big script, its line numbering may be different than when it is run in non-compiled mode.

The full path and name of the file to which A_LineNumber belongs. If the script was loaded from an external file, this is the same as A_ScriptFullPath unless the line belongs to one of the script's #Include files.

If the script was compiled based on a .bin file, this is the full path and name of the current executable file, the same as A_ScriptFullPath.

If the script is embedded, A_LineFile contains an asterisk (*) followed by the resource name; e.g. *#1

For non-compiled or embedded scripts: The full path and name of the EXE file that is actually running the current script. For example: C:\Program Files\AutoHotkey\AutoHotkey.exe

For compiled scripts based on a .bin file, the value is determined by reading the installation directory from the registry and appending "\AutoHotkey.exe". If AutoHotkey is not installed, the value is blank. The example below is equivalent:

InstallDir := RegRead("HKLM\SOFTWARE\AutoHotkey", "InstallDir", "")
AhkPath := InstallDir ? InstallDir "\AutoHotkey.exe" : ""

For compiled scripts based on an .exe file, A_AhkPath contains the full path of the compiled script. This can be used in combination with /script to execute external scripts. To instead locate the installed copy of AutoHotkey, read the registry as shown above.

Current 4-digit year (e.g. 2004). Synonymous with A_Year.

Note: To retrieve a formatted time or date appropriate for your locale and language, use FormatTime() (time and long date) or FormatTime(, "LongDate") (retrieves long-format date).

Current 2-digit minute (00-59).

The current local time in YYYYMMDDHH24MISS format.

Note: Date and time math can be performed with DateAdd and DateDiff. Also, FormatTime can format the date and/or time according to your locale or preferences.

The number of milliseconds that have elapsed since the system was started, up to 49.7 days. By storing A_TickCount in a variable, elapsed time can later be measured by subtracting that variable from the latest A_TickCount value. For example:

StartTime := A_TickCount
Sleep 1000
ElapsedTime := A_TickCount - StartTime
MsgBox ElapsedTime " milliseconds have elapsed."

If you need more precision than A_TickCount's 10 ms, use QueryPerformanceCounter().

Returns a Menu object which can be used to modify or display the tray menu.

Can be used to get or set whether the script's main window is allowed to be opened via the tray icon. Possible values are 0 (forbidden) and 1 (allowed).

If the script is neither compiled nor embedded, this variable defaults to 1, otherwise this variable defaults to 0 but can be overridden by assigning it a value. Setting it to 1 also restores the "Open" menu item to the tray menu and enables the items in the main window's View menu such as "Lines most recently executed", which allows viewing of the script's source code and other info.

The following functions are always able to show the main window and select the corresponding View options when they are encountered in the script at runtime: ListLines, ListVars, ListHotkeys, and KeyHistory.

Setting it to 1 does not prevent the main window from being shown by WinShow or inspected by ControlGetText or similar methods, but it does prevent the script's source code and other info from being exposed via the main window, except when one of the functions listed above is called by the script.

Can be used to get or set the tray icon's tooltip text, which is displayed when the mouse hovers over it. If blank, the script's name is used instead.

To create a multi-line tooltip, use the linefeed character (`n) in between each line, e.g. "Line1`nLine2". Only the first 127 characters are displayed, and the text is truncated at the first tab character, if present.

On Windows 10 and earlier, to display tooltip text containing ampersands (&), escape each ampersand with two additional ampersands. For example, assigning "A &&& B" would display "A & B" in the tooltip.

The number of milliseconds that have elapsed since the system last received keyboard, mouse, or other input. This is useful for determining whether the user is away. Physical input from the user as well as artificial input generated by any program or script (such as the Send or MouseMove functions) will reset this value back to zero. Since this value tends to increase by increments of 10, do not check whether it is equal to another value. Instead, check whether it is greater or less than another value. For example:

if A_TimeIdle > 600000
    MsgBox "Last activity was 10 minutes ago"

The most recently executed hotkey or non-auto-replace hotstring (blank if none), e.g. #z. This value will change if the current thread is interrupted by another hotkey or hotstring, so it is generally better to use the parameter ThisHotkey when available.

When a hotkey is first created -- either by the Hotkey function or the double-colon syntax in the script -- its key name and the ordering of its modifier symbols becomes the permanent name of that hotkey, shared by all variants of the hotkey.

When a hotstring is first created -- either by the Hotstring function or a double-colon label in the script -- its trigger string and sequence of option characters becomes the permanent name of that hotstring.

Contains the same string as the ComSpec environment variable, which is usually the full path to the command prompt executable (cmd.exe). Often used with Run/RunWait. For example:

C:\Windows\system32\cmd.exe

The full path and name of the folder designated to hold temporary files. It is retrieved from one of the following locations (in order): 1) the environment variables TMP, TEMP, or USERPROFILE; 2) the Windows directory. For example:

C:\Users\<UserName>\AppData\Local\Temp

The version number of the operating system, in the format "major.minor.build". For example, Windows 7 SP1 is 6.1.7601.

Applying compatibility settings in the AutoHotkey executable or compiled script's properties causes the OS to report a different version number, which is reflected by A_OSVersion.

The Program Files directory (e.g. C:\Program Files or C:\Program Files (x86)). This is usually the same as the ProgramFiles environment variable.

On 64-bit systems (and not 32-bit systems), the following applies:

• If the executable (EXE) that is running the script is 32-bit, A_ProgramFiles returns the path of the "Program Files (x86)" directory.
• For 32-bit processes, the ProgramW6432 environment variable contains the path of the 64-bit Program Files directory. On Windows 7 and later, it is also set for 64-bit processes.
• The ProgramFiles(x86) environment variable contains the path of the 32-bit Program Files directory.

The full path and name of the folder containing the current user's application-specific data. For example:

C:\Users\<UserName>\AppData\Roaming

The full path and name of the folder containing the all-users application-specific data. For example:

C:\ProgramData

The full path and name of the folder containing the current user's desktop files. For example:

C:\Users\<UserName>\Desktop

The full path and name of the folder containing the all-users desktop files. For example:

C:\Users\Public\Desktop

The full path and name of the current user's Start Menu folder. For example:

C:\Users\<UserName>\AppData\Roaming\Microsoft\Windows\Start Menu

The full path and name of the all-users Start Menu folder. For example:

C:\ProgramData\Microsoft\Windows\Start Menu

The full path and name of the Programs folder in the current user's Start Menu. For example:

C:\Users\<UserName>\AppData\Roaming\Microsoft\Windows\Start Menu\Programs

The full path and name of the Programs folder in the all-users Start Menu. For example:

C:\ProgramData\Microsoft\Windows\Start Menu\Programs

The full path and name of the Startup folder in the current user's Start Menu. For example:

C:\Users\<UserName>\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup

The full path and name of the Startup folder in the all-users Start Menu. For example:

C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup

The full path and name of the current user's "My Documents" folder. Unlike most of the similar variables, if the folder is the root of a drive, the final backslash is not included (e.g. it would contain M: rather than M:\). For example:

C:\Users\<UserName>\Documents

Contains 1 if the current user has admin rights, otherwise 0.

To have the script restart itself as admin (or show a prompt to the user requesting admin), use Run *RunAs. However, note that running the script as admin causes all programs launched by the script to also run as admin. For a possible alternative, see the FAQ.

A_ScreenWidth
A_ScreenHeight

The width and height of the primary monitor, in pixels (e.g. 1024 and 768).

To discover the dimensions of other monitors in a multi-monitor system, use SysGet.

To instead discover the width and height of the entire desktop (even if it spans multiple monitors), use the following example:

VirtualWidth := SysGet(78)
VirtualHeight := SysGet(79)

In addition, use SysGet to discover the work area of a monitor, which can be smaller than the monitor's total area because the taskbar and other registered desktop toolbars are excluded.

The type of mouse cursor currently being displayed. It will be one of the following words: AppStarting, Arrow, Cross, Help, IBeam, Icon, No, Size, SizeAll, SizeNESW, SizeNS, SizeNWSE, SizeWE, UpArrow, Wait, Unknown. The acronyms used with the size-type cursors are compass directions, e.g. NESW = NorthEast+SouthWest. The hand-shaped cursors (pointing and grabbing) are classified as Unknown.

Contains additional information about the following events:

• Mouse wheel hotkeys (WheelDown/Up/Left/Right)
• OnMessage
• Regular Expression Callouts

Note: Unlike variables such as A_ThisHotkey, each thread retains its own value for A_EventInfo. Therefore, if a thread is interrupted by another, upon being resumed it will still see its original/correct values in these variables.

A_EventInfo can also be set by the script, but can only accept unsigned integers within the range available to pointers (32-bit or 64-bit depending on the version of AutoHotkey).

This is usually the result from the OS's GetLastError() function after the script calls certain functions, including DllCall, Run/RunWait, File/Ini/Reg functions (where documented) and possibly others. A_LastError is a number between 0 and 4294967295 (always formatted as decimal, not hexadecimal). Zero (0) means success, but any other number means the call failed. Each number corresponds to a specific error condition. See OSError for how to get the localized error description text, or search www.microsoft.com for "system error codes" to get a list. A_LastError is a per-thread setting; that is, interruptions by other threads cannot change it.

Assigning a value to A_LastError also causes the OS's SetLastError() function to be called.

Contain 1 and 0. They can be used to make a script more readable. For details, see Boolean Values.

These are actually keywords, not variables.