Vbscript Free Tutorial

VBScript Syntax Quick Reference

VBScript is composed of a great deal of syntax you need to keep straight. You will probably use many elements of the syntax so often that you will easily remember what they do. However, even an experienced programmer uses some of the syntax elements infrequently. When you come across those elements in your code or strain to remember if you have the syntax exactly right, a good reference can serve as a welcome relief.

Languages such as Visual Basic 4.0 come complete with a very useful context-sensitive help facility. VBScript provides no such inherent support. It is a hosted language that comes along for the ride with the environment that supports it, such as a browser. It is not a separate product with its own development environment and the help that is typical of such an environment. You can turn to other places for help on the Internet, however. At the time of this writing, Microsoft had a very helpful VBScript language reference that could be reached at http://www.microsoft.com/vbscript.

This appendix is intended to supplement the VBScript information available from the Web location. Unlike some of the other language references available, the information in this appendix is presented in an alphabetical fashion, intermixing functions, statements, intrinsic constants, and major properties in the same list. A brief description of each element is provided, but it's not enough to replace the official reference material-just enough to give you a quick, high-level understanding of what that element does.

You'll develop a common way to refer to information as you work your way through a new guide or sample programs. You might find a language element that is unfamiliar, but all you need to do to quickly get back on course is see a brief description of what it does and find out if it is a property, function, or other type of construct. This appendix can serve as a quick first resort for such information.

Table A.1. Summary of VBScript syntax.

Symbol	Type	Description
`+` (addition)	Operator	Adds two numbers together. You can also use this to concatenate strings.
`'` (comment indicator)	Keyword	What follows this symbol on the line is a comment.
`"` (double quote)	Keyword	Shows the start and end of a literal string.
`&` (string concat-enation)	Operator	Performs the concatenation of two string expressions.
`/` (division, floating point)	Operator	Divides two numbers and returns a floating-point result.
`\` (division, integer)	Operator	Divides two numbers and returns an integer result.
`=` (equals)	Comparison	Checks whether two expressions are equivalent.
`^` (exponent)	Operator	Raises a number to the power of an exponent.
`>` (greater than)	Comparison	Checks whether the left-side expression is greater than the right-side expression.
`>=` (greater than or equal)	Comparison	Checks whether the left-side expression isgreater than or equal to the right-side expression.
`<` (less than)	Comparison	Checks whether the left-side expression is less than the right-side expression.
`<=` (less than or equal)	Comparison	Checks whether the left-side expression is less than or equal to the right-side expression.
`_` (line continuation character)-	Keyword	Indicates that the current line continues onto the next line.
`*` (multiplication)	Operator	Multiplies two numbers.
`-` (subtraction or indicator)	Operator	Finds the difference between two numbers; or, when applied to one operand, treats it as a negative value.
`:` (colon)		Indicates line separation, as in `A = A + 1 : B = C + 1`.
`<>` (not equal)	Comparison	Checks whether two expressions are not equivalent.
`Abs`	Function	Returns the absolute value of a number.
`And`	Logical operator	Performs a logical conjunction on two expressions.
`Array`	Function	Returns a variant comprising an array.
`Asc`	Function	Provides the character code corresponding to the first letter in a string as a return code.
`AscB`	Function	Like `Asc`, but returns the first byte rather than the first character of a string.
`Atn`	Function	Provides the arctangent of a number as a return code.
`Call`	Statement	Calls a procedure.
`CBool`	Function	Provides as a return code an expression that has been converted to a variant of subtype `Boolean`.
`Cbyte`	Function	Provides as a return code an expression that has been converted to a variant of subtype `Byte`.
`CDate`	Function	Provides as a return code an expression that has been converted to a variant of subtype `Date`.
`CDbl`	Function	Provides as a return code an expression that has been converted to a variant of subtype `Double`.
`Chr`	Function	Provides as a return code the character associated with the ASCII code. This function can return 1 or 2 bytes.
`ChrB`	Function	Returns the byte associated with the ASCII code.
`Cint`	Function	Provides as a return code an expression that has been converted to a variant of subtype `Integer`.
`Clear`	Method for the `Err` object	Results in resetting all of the `Err` objects properties to a no-error state.
`CLng`	Function	Provides as a return code an expression that has been converted to a variant of subtype `Long`.
`Cos`	Function	Provides as a return code the cosine of an angle.
`CSng`	Function	Provides as a return code an expression that has been converted to a variant of subtype `Single`.
`CStr`	Function	Provides as a return code an expression that has been converted to a variant of subtype `String`.
`CVErr`	Function	Provides as a return code a variant of subtype `Error` containing a user-provided error code.
`Date`	Function	Returns the current system date.
`DateSerial`	Function	Provides as a return code a variant of subtype `Date` for the given month, day, and year.
`DateValue`	Function	Provides as a return code a variant of subtype `Date` for the given string.
`Day`	Function	Provides as a return code a whole number of 1 through 31, representing the day of the month for the given date string.
`Description`	Property for he `Err` object	The string that describes the current error.
`Dim`	Statement	Declares variables.
`Do…Loop`	Statement	Repeats a block of code while a condition is `True` or until a condition becomes `True`.
`Empty`	Literal	Signifies that a variable is uninitialized.
`Erase`	Statement	Reinitializes fixed-size array elements and frees the storage space of dynamic arrays.
`Err`	Object	Provides information about run-time errors.
`Eqv`	Logical operator	Performs logical equivalence for the two expressions provided as operands.
`Exit Do`	Statement	Exits a `Do…Loop` code block.
`Exit For`	Statement	Exits a `For…Next` code block.
`Exit Function`	Statement	Exits a function.
`Exit Sub`	Statement	Exits a procedure.
`Exp`	Function	Returns e (the base of natural logarithms) raised to a power.
`Fix`	Function	Provides the integer portion of a number as a return code; if the number is negative, it provides the first number greater than the operand.
`For…Next`	Statement	Repeats a group of statements a designated number of times.
`For Each…Next`	Statement	Repeats a group of statements for each element in an array or a collection.
`Function`	Statement	Declares a procedure-level block of code that returns a value when called.
`HelpContext`	Property for	The context ID in a corresponding help the `Err` objectfile for the current error.
`HelpFile`	Property for the `Err` object	The corresponding help file for the current error.
`Hex`	Function	Provides as a return code a string repre-senting the hexadecimal value of a number.
`Hour`	Function	Provides as a return code a whole number from 0 through 23, representing the hour of the day.
`If…Then…Else`	Statement	Executes a group of statements, depending on the value of an expression.
`Imp`	Logical operator	Performs a logical implication on the two operands provided.
`InputBox`	Function	Displays a dialog box with a prompt, appropriate buttons, and an input text box and then returns the input text and button response to the calling program.
`Int`	Function	Provides the integer portion of a number as a return code; if the number is negative, it provides the first number less than the operand.
`InStr`	Function	Provides the position indicator of the first character of the target string within the search string.
`InstrB`	Function	Provides the position indicator of the first byte of the target string within the search string.
`Is`	Operator	Compares two object reference variables.
`IsArray`	Function	Provides as a return code a `Boolean` value signifying whether a variable is an array.
`IsDate`	Function	Provides as a return code a `Boolean` value signifying whether an expression can be converted to a date.
`IsEmpty`	Function	Provides as a return code a `Boolean` value signifying whether a variable has been initialized.
`IsError`	Function	Provides as a return code a `Boolean` value signifying whether an expression is an error value.
`IsNull`	Function	Provides as a return code a `Boolean` value signifying whether an expression contains no valid data (`Null`).
`IsNumeric`	Function	Provides as a return code a `Boolean` value signifying whether an expression can be evaluated as a number.
`IsObject`	Function	Provides as a return code a `Boolean` value signifying whether an expression repre-sents an OLE automation object.
`LBound`	Function	Provides as a return code the smallest available subscript for the stated dimen-sion of an array.
`Lcase`	Function	Provides as a return code a string that has been converted to lowercase.
`Left`	Function	Provides as a return code a specified number of characters from the left side of a string.
`Len`	Function	Provides as a return code the number of characters in a string or the number of bytes required to store a variable.
`LenB`	Function	Provides as a return code the number of bytes in a string or the number of bytes required to store a variable.
`Log`	Function	Provides as a return code the natural logarithm of a number.
`Ltrim`	Function	Provides a string that has leading (leftmost) spaces removed.
`Mid`	Function	Provides as a return code a described number of characters from a string.
`Minute`	Function	Provides as a return code a whole number from 0 through 59, representing the minute of the hour.
`Mod`	Operator	Divides two numbers and returns only the remainder.
`Month`	Function	Provides as a return code a whole number from 1 through 12, representing the month of the year.
`MsgBox`	Function	Shows a given prompt in a message dialog box with a button and returns the user's button response.
`Not`	Logical operator	Checks for logical `Not` equivalent condition.
`Nothing`	Literal	Removes reference and frees memory.
`Now`	Function	Returns the current setting of your computer's system date and time.
`Null`	Literal	Indicates no valid data state, as opposed to `Empty`, which indicates no data was ever assigned.
`Number`	Property for the `Err` object	The numeric error code for the current error.
`Oct`	Function	Provides as a return code a string repre-senting the octal value of a number.
`On Error ResumeNext`	Statement	Indicates that if an error occurs, control should resume at next statement.
`Option Explicit`	Statement	Indicates that variables must be declared.
`Or`	Operator	Performs a logical disjunction on two expressions.
`Raise`	Method for the `Err` object	Forces a run-time error to be raised.
`Randomize`	Statement	Starts a sequence for the random-number generator.
`ReDim`	Statement	Allocates or reallocates storage space and declares dynamic-array variables at the procedure level.
`Rem`	Statement	Used to include comments in a program. The single quote, which achieves the same purpose, is used more often.
`Right`	Function	Provides as a return code a described number of characters from the right side of a string.
`Rnd`	Function	Provides a random number as a return code.
`Rtrim`	Function	Provides a string that has trailing (rightmost) spaces removed.
`Second`	Function	Provides as a return code a whole number from 0 through 59, representing the second of the minute.
`Set`	Statement	Assigns an object reference.
`Sgn`	Function	Provides as a return code an integer disclosing the sign of a number.
`Sin`	Function	Provides as a return code the sine of an angle.
`Source`	Property for the `Err` object	The source of the error for the current error.
`Space`	Function	Returns the given number of spaces.
`Sqr`	Function	Provides as a return code the square root of a number.
`Static`	Statement (Procedure-level)	Declares a persistent variable. Contents will be retained from one call to the next.
`StrComp`	Function	Returns a value signifying the outcome of a string comparison.
`String`	Function	Returns a repeating character string of the number of characters described.
`Sub`	Statement	Declares procedures that do not provide a return code.
`Tan`	Function	Provides as a return code the tangent of an angle.
`Time`	Function	Returns a variant of subtype `Date` showing the current system time.
`TimeSerial`	Function	Returns a variant of subtype `Date` comprising the time for a specific hour, minute, and second.
`TimeValue`	Function	Returns a variant of subtype `Date` containing the time.
`Trim`	Function	Provides as a return code a duplicate of a string without leading spaces (`LTrim`), trailing spaces (`RTrim`), or both leading and trailing spaces (`Trim`).
`Ubound`	Function	Provides as a return code the largest available subscript for the indicated dimension of an array.
`Ucase`	Function	Returns a string that has been converted to uppercase.
`Val`	Function	Returns the numbers enclosed in a string. Not supported in current beta.
`VarType`	Function	Returns a value disclosing the subtype of a variable.
`vbAbort`	(See footnote*)	Applies to the `MsgBox` function; `Value = 3` indicates abort.
`vbAbortRetryIgnore`	(See footnote*)	Applies to the `MsgBox` function; `Value = 2` displays Abort, Retry, and Ignore buttons.
`vbApplicationModal`	(See footnote*)	Applies to the `MsgBox` function; `Value = 0` indicates that the application is modal. The user must respond to the message box before continuing work in the current application.
`vbArray`	(See footnote*)	Applies to the `VarType` function; `Value = 8192` indicates array.
`vbBoolean`	(See footnote*)	Applies to the `VarType` function; `Value = 11` indicates `Boolean.`
`vbByte`	(See footnote*)	Applies to the `VarType` function; `Value = 17` indicates byte.
`vbCancel`	(See footnote*)	Applies to the `MsgBox` function; `Value = 2` indicates cancel.
`vbCr`	(See footnote*)	General purpose; indicates carriage-return character.
`vbCritical`	(See footnote*)	Applies to the `MsgBox` function; `Value = 16` displays critical message icon.
`vbCrLf`	(See footnote*)	General purpose; indicates carriage-return and line-feed characters.
`vbCurrency`	(See footnote*)	Applies to the `VarType` function; `Value = 6` indicates currency.
`vbDataObject`	(See footnote*)	Applies to the `VarType` function; `Value = 13` indicates non-OLE automa-tion object.
`vbDate`	(See footnote*)	Applies to the `VarType` function; `Value = 7` indicates date.
`vbDefaultButton1`	(See footnote*)	Applies to the `MsgBox` function; `Value = 0` indicates the first button is the default.
`vbDefaultButton2`	(See footnote*)	Applies to the `MsgBox` function; `Value = 256` indicates the second button is the default.
`vbDefaultButton3`	(See footnote*)	Applies to the `MsgBox` function; `Value = 512` indicates the third button is the default.
`vbDouble`	(See footnote*)	Applies to the `VarType` function; `Value = 5` indicates a double-precision, floating-point number.
`vbEmpty`	(See footnote*)	Applies to the `VarType` function; `Value = 0` indicates empty.
`vbError`	(See footnote*)	Applies to the `VarType` function; `Value = 10` indicates error.
`vbExclamation`	(See footnote*)	Applies to the `MsgBox` function; `Value = 48` displays the warning message icon.
`vbFalse`	(See footnote*)	General purpose; indicates `Boolean` value represented by `0`.
`vbFriday`	(See footnote*)	Applies to the `Weekday` function; `Value = 6` indicates Friday.
`vbIgnore`	(See footnote*)	Applies to the `MsgBox` function; `Value = 5` indicates ignore.
`vbInformation`	(See footnote*)	Applies to the `MsgBox` function; `Value = 64` displays information message icon.
`vbInteger`	(See footnote*)	Applies to the `VarType` function; `Value = 2` indicates integer.
`vbLf`	(See footnote*)	General purpose; indicates line-feed character.
`vbLong`	(See footnote*)	Applies to the `VarType` function; `Value = 3` indicates long integer.
`vbMonday`	(See footnote*)	Applies to the `Weekday` function; `Value = 2` indicates Monday.
`vbNo`	(See footnote*)	Applies to the `MsgBox` function; `Value = 7` indicates no.
`vbNull`	(See footnote*)	Applies to the `VarType` function; `Value = 1` indicates null.
`vbObject`	(See footnote*)	Applies to the `VarType` function; `Value = 9` indicates OLE automation object.
`vbObjectError`	(See footnote*)	Indicates an object-generated error.
`vbOK`	(See footnote*)	Applies to the `MsgBox` function; `Value = 1` indicates OK.
`vbOKCancel`	(See footnote*)	Applies to `MsgBox` function; `Value = 1` displays OK and Cancel buttons.
`vbOKOnly`	(See footnote*)	Applies to the `MsgBox` function; `Value = 0` displays OK button only.
`vbQuestion`	(See footnote*)	Applies to the `MsgBox` function; `Value = 32` displays warning query icon.
`vbRetry`	(See footnote*)	Applies to the `MsgBox` function; `Value = 4` indicates retry.
`vbRetryCancel`	(See footnote*)	Applies to the `MsgBox` function; `Value = 5` displays Retry and Cancel buttons.
`vbSaturday`	(See footnote*)	Applies to the `Weekday` function; `Value = 7` indicates Saturday.
`vbSingle`	(See footnote*)	Applies to the `VarType` function; `Value = 4` indicates single-precision, floating-point number.
`vbString`	(See footnote*)	Applies to the `VarType` function; `Value = 8` indicates string.
`vbSunday`	(See footnote*)	Applies to the `Weekday` function; `Value = 1` indicates Sunday.
`vbSystemModal`	(See footnote*)	Applies to the `MsgBox` function; `Value = 4096` indicates system modal. All applications are suspended until the user responds to the message box.
`vbThursday`	(See footnote*)	Applies to the `Weekday` function; `Value = 5` indicates Thursday.
`vbTrue`	(See footnote*)	General purpose; indicates `Boolean` value represented by `-1`.
`vbTuesday`	(See footnote*)	Applies to the `Weekday` function; `Value = 3` indicates Tuesday.
`vbUseSystem`	(See footnote*)	Applies to the `Weekday` function; `Value = 0` uses the NLS API setting.
`vbVariant`	(See footnote*)	Applies to the `VarType` function; `Value = 12` indicates variant.
`vbWednesday`	(See footnote*)	Applies to the `Weekday` function; `Value = 4` indicates Wednesday.
`vbYes`	(See footnote*)	Applies to the `MsgBox` function; `Value = 6` indicates yes.
`vbYesNo`	(See footnote*)	Applies to the `MsgBox` function; `Value = 4` displays Yes and No buttons.
`vbYesNoCancel`	(See footnote*)	Applies to the `MsgBox` function; `Value = 3` displays Yes, No, and Cancel buttons.
`Weekday`	Function	Returns a whole number showing the day of the week.
`While…Wend`	Statement	Performs a series of statements as long as a given condition is `True`.
`Xor`	Logical operator	Performs logical exclusion on the operands.
`Year`	Function	Returns a whole number showing the year for the date string representation.
*The symbols with the `vb` prefix are values expected by various VBScript functions. In Visual Basic these are intrinsic contants. In VBScript, you must declare these as variables if you wish to treat them as constants since there is no direct constant support.