VBScript Tutorial - Lesson 7: Built-In Functions

Built-In Functions

Introduction

VBScript ships with many functions that you can use to complete your scripts. These functions are highly reliable and can tremendously reduce your work. This means that, before creating your own procedure or function, first make sure it has not been written already because if an existing function already implements the behavior you want to apply, you should such a function.

Because VBScript is an interpreted language (and not a compiled language), all of the possible built-in functions are already known to the browser. Therefore, you don't need to include a file or library.

The best place to find out what functions already exist is by consulting the MSDN library or web site for its documentation.

Conversion Functions

We saw already that the users of your web pages will be presented with objects called controls. These objects allow the user to type values or select something from a list. Anything the user types in a text-based field is primarily considered as a string. Before performing any type of operation that involves such a value, you should make sure you can identify what kind of value it is. For example, you shouldn't try to multiply a string by a date such as FirstName * January 16. Although you will not be able to avoid every single type of problem that could occur in a page, you can reduce errors by checking the value that a control holds.

The first thing you should do with a value retrieved from a control is to convert it to the appropriate type. There are various conversion functions adapted to the different possible kinds of values. The general syntax of the conversion functions is:

ReturnType = Function(Expression)

The expression could be of any kind, depending on how the expression would be supplied. For example, it could be a string or value the user would have entered in form. It could also be the result of a calculation performed on another procedure or function. The function would take such a value, string, or expression and attempt to convert. If the conversion is successful, the function would return a new value that is of the type specified by the ReturnType in our syntax.

The conversion functions are as follows:

Function
Name	Return Type	Description
CBool	Boolean	Converts an expression into a Boolean value
CByte	Byte	Converts an expression into Byte number
CDate	Date	Converts and expression into a date or time value
CDbl	Double	Converts an expression into a flowing-point (decimal) number
CInt	Integer	Converts an expression into an integer (natural) number
CCur	Currency	Converts an expression into a currency (monetary) value
CLng	Long	Converts an expression into a long integer (a large natural) number
CSng	Single	Converts an expression into a flowing-point (decimal) number
CStr	String	Converts an expression into a string

Practical Learning:

Start your text editor.

In the empty file, type the following:

<html>
<head>
<Script Language="VBScript">
<!--
Sub GiveFocus
  Document.EmployeesPayroll.txtFirstName.Focus()
End Sub
-->
</Script>

<title>Employees Payroll</title>
</head>

<body>

<h1>Oddenton Auto Repair</h1>
<h2>Employees Payroll</h2>
<form name="EmployeesPayroll" method="POST">
  <table border="0" width="548">
    <tr>
      <td width="104">First Name:</td>
      <td width="430"><input type="text" name="txtFirstName" size="20"></td>
    </tr>
    <tr>
      <td width="104">LastName:</td>
      <td width="430"><input type="text" name="txtLastName" size="20"></td>
    </tr>
  </table>
  
  <table border="0" width="548">
    <tr>
      <td width="104">Hourly Salary</td>
      <td width="428"><input type="text" name="txtHourlySalary" size="10"value="0.00"></td>
    </tr>
  </table>
  <table border="0" width="563">
    <tr>
      <td width="124">Weekly Hours</td>
      <td width="62" align="center">Mon</td>
      <td width="62" align="center">Tue</td>
      <td width="62" align="center">Wed</td>
      <td width="62" align="center">Thu</td>
      <td width="62" align="center">Fri</td>
      <td width="62" align="center">Sat</td>
      <td width="62" align="center">Sun</td>
    </tr>
    <tr>
      <td width="124"></td>
      <td width="62" align="center"><input type="text" name="txtMon" size="6" value="0.00"></td>
      <td width="62" align="center"><input type="text" name="txtTue" size="6" value="0.00"></td>
      <td width="62" align="center"><input type="text" name="txtWed" size="6" value="0.00"></td>
      <td width="62" align="center"><input type="text" name="txtThu" size="6" value="0.00"></td>
      <td width="62" align="center"><input type="text" name="txtFri" size="6" value="0.00"></td>
      <td width="62" align="center"><input type="text" name="txtSat" size="6" value="0.00"></td>
      <td width="62" align="center"><input type="text" name="txtSun" size="6" value="0.00"></td>
    </tr>
  </table>
  <table border="0" width="558">
    <tr>
      <td width="104"></td>
      <td width="440">
        <p><input type="button" value="Process" name="btnProcess">
           &nbsp;&nbsp;
	   <input type="reset" value="Reset" name="B2">
        </p>
      </td>
    </tr>
  </table>
</form>
</body>

</html>

Save the file as payroll2.htm in the vbstutorial folder and preview it in the browser:
After previewing the page, return to your text editor.

To perform calculations that involve values stored in text boxes, change the file as follows:

<html>
<head>
<Script Language="VBScript">
<!--
' -- This procedure gives focus to the First Name text box
Sub GiveFocus
  Document.EmployeesPayroll.txtFirstName.Focus()
End Sub

' This function retrieves the first and last names
' It concatenates them and returns a full name
Function GetFullName()
  Dim FirstName, LastName

  FirstName = Document.EmployeesPayroll.txtFirstName.Value
  LastName  = Document.EmployeesPayroll.txtLastName.Value

  GetFullName = LastName & ", " & FirstName
End Function

' This function uses an hourly salary and the number of hours in a week
' It calculates the total earnings for the week
Function CalculateWeeklySalary(HourlySalary, WeeklyHours)
  CalculateWeeklySalary = HourlySalary * WeeklyHours
End Function

' This is the central procedure of the script
' It processes the form and displays the values in the other form
Sub ProcessPayroll()
  Dim dMon, dTue, dWed, dThu, dFri, dSat, dSun, TotalHours
  Dim HourlySalary, WeeklySalary
  Dim FullName

  dMon = CDbl(Document.EmployeesPayroll.txtMon.Value)
  dTue = CDbl(Document.EmployeesPayroll.txtTue.Value)
  dWed = CDbl(Document.EmployeesPayroll.txtWed.Value)
  dThu = CDbl(Document.EmployeesPayroll.txtThu.Value)
  dFri = CDbl(Document.EmployeesPayroll.txtFri.Value)
  dSat = CDbl(Document.EmployeesPayroll.txtSat.Value)
  dSun = CDbl(Document.EmployeesPayroll.txtSun.Value)

  HourlySalary = Document.EmployeesPayroll.txtHourlySalary.Value

  TotalHours   = dMon + dTue + dWed + dThu + dFri + dSat + dSun
  WeeklySalary = CalculateWeeklySalary(HourlySalary, TotalHours)
  FullName     = GetFullName()


  PayrollResults.txtFullName.Value       = FullName
  PayrollResults.txtWeeklyEarnings.Value = "$" & WeeklySalary
End Sub
-->
</Script>

<title>Employees Payroll</title>
</head>

<body OnLoad="GiveFocus()">

<h1>Odenton Auto Repair</h1>
<h2>Employees Payroll</h2>
<form name="EmployeesPayroll" method="POST">
  <table border="0" width="548">
    <tr>
      <td width="104">First Name:</td>
      <td width="430"><input type="text" name="txtFirstName" size="20"></td>
    </tr>
    <tr>
      <td width="104">LastName:</td>
      <td width="430"><input type="text" name="txtLastName" size="20"></td>
    </tr>
  </table>
  
  <table border="0" width="548">
    <tr>
      <td width="104">Hourly Salary</td>
      <td width="428"><input type="text" name="txtHourlySalary" size="10" value="0.00"></td>
    </tr>
  </table>
  <table border="0" width="563">
    <tr>
      <td width="124">Weekly Hours</td>
      <td width="62" align="center">Mon</td>
      <td width="62" align="center">Tue</td>
      <td width="62" align="center">Wed</td>
      <td width="62" align="center">Thu</td>
      <td width="62" align="center">Fri</td>
      <td width="62" align="center">Sat</td>
      <td width="62" align="center">Sun</td>
    </tr>
    <tr>
      <td width="124"></td>
      <td width="62" align="center"><input type="text" name="txtMon" size="6" value="0.00"></td>
      <td width="62" align="center"><input type="text" name="txtTue" size="6" value="0.00"></td>
      <td width="62" align="center"><input type="text" name="txtWed" size="6" value="0.00"></td>
      <td width="62" align="center"><input type="text" name="txtThu" size="6" value="0.00"></td>
      <td width="62" align="center"><input type="text" name="txtFri" size="6" value="0.00"></td>
      <td width="62" align="center"><input type="text" name="txtSat" size="6" value="0.00"></td>
      <td width="62" align="center"><input type="text" name="txtSun" size="6" value="0.00"></td>
    </tr>
  </table>
  <table border="0" width="558">
    <tr>
      <td width="104"></td>
      <td width="440">
        <p><input type="button" value="Process" name="btnProcess" OnClick="ProcessPayroll()">
           &nbsp;&nbsp;
	   <input type="reset" value="Reset" name="B2">
        </p>
      </td>
    </tr>
  </table>
</form>

<hr>

<form name="PayrollResults">
<table border="0" width="546">
  <tr>
    <td width="113">Full Name:</td>
    <td width="419"><input type="text" name="txtFullName" size="20"></td>
  </tr>
</table>
<table border="0" width="545">
  <tr>
    <td width="112">Weekly Earnings:</td>
    <td width="419"><input type="text" name="txtWeeklyEarnings" size="20" value="$0.00"></td>
  </tr>
</table>
</form>

</body>

</html>

Save the file and preview it in the browser. Type the first and last names in the corresponding fields.
Type the employees hours for each day and click the Process button
After previewing the page, return to your text editor.

Besides the conversion functions, VBScript provides many other functions you can use in your scripts. Some of these functions are:

Language Element	Description
Abs Function	Returns the absolute value of a number.
Array Function	Returns a Variant containing an array.
Asc Function	Returns the ANSI character code corresponding to the first letter in a string.
Atn Function	Returns the arctangent of a number.
CBool Function	Returns an expression that has been converted to a Variant of subtype Boolean.
CByte Function	Returns an expression that has been converted to a Variant of subtype Byte.
CCur Function	Returns an expression that has been converted to a Variant of subtype Currency.
CDate Function	Returns an expression that has been converted to a Variant of subtype Date.
CDbl Function	Returns an expression that has been converted to a Variant of subtype Double.
Chr Function	Returns the character associated with the specified ANSI character code.
CInt Function	Returns an expression that has been converted to a Variant of subtype Integer.
CLng Function	Returns an expression that has been converted to a Variant of subtype Long.
Cos Function	Returns the cosine of an angle.
CreateObject Function	Creates and returns a reference to an Automation object.
CSng Function	Returns an expression that has been converted to a Variant of subtype Single.
CStr Function	Returns an expression that has been converted to a Variant of subtype String.
Date Function	Returns the current system date.
DateAdd Function	Returns a date to which a specified time interval has been added.
DateDiff Function	Returns the number of intervals between two dates.
DatePart Function	Returns the specified part of a given date.
DateSerial Function	Returns a Variant of subtype Date for a specified year, month, and day.
DateValue Function	Returns a Variant of subtype Date.
Day Function	Returns a whole number between 1 and 31, inclusive, representing the day of the month.
Eval Function	Evaluates an expression and returns the result.
Exp Function	Returns e (the base of natural logarithms) raised to a power.
Filter Function	Returns a zero-based array containing subset of a string array based on a specified filter criteria.
Fix Function	Returns the integer portion of a number.
FormatCurrency Function	Returns an expression formatted as a currency value using the currency symbol defined in the system control panel.
FormatDateTime Function	Returns an expression formatted as a date or time.
FormatNumber Function	Returns an expression formatted as a number.
FormatPercent Function	Returns an expression formatted as a percentage (multiplied by 100) with a trailing % character.
GetLocale Function	Returns the current locale ID value.
GetObject Function	Returns a reference to an Automation object from a file.
GetRef Function	Returns a reference to a procedure that can be bound to an event.
Hex Function	Returns a string representing the hexadecimal value of a number.
Hour Function	Returns a whole number between 0 and 23, inclusive, representing the hour of the day.
InputBox Function	Displays a prompt in a dialog box, waits for the user to input text or click a button, and returns the contents of the text box.
InStr Function	Returns the position of the first occurrence of one string within another.
InStrRev Function	Returns the position of an occurrence of one string within another, from the end of string.
Int Function	Returns the integer portion of a number.
IsArray Function	Returns a Boolean value indicating whether a variable is an array.
IsDate Function	Returns a Boolean value indicating whether an expression can be converted to a date.
IsEmpty Function	Returns a Boolean value indicating whether a variable has been initialized.
IsNull Function	Returns a Boolean value that indicates whether an expression contains no valid data (Null).
IsNumeric Function	Returns a Boolean value indicating whether an expression can be evaluated as a number.
IsObject Function	Returns a Boolean value indicating whether an expression references a valid Automation object.
Join Function	Returns a string created by joining a number of substrings contained in an array.
LBound Function	Returns the smallest available subscript for the indicated dimension of an array.
LCase Function	Returns a string that has been converted to lowercase.
Left Function	Returns a specified number of characters from the left side of a string.
Len Function	Returns the number of characters in a string or the number of bytes required to store a variable.
LoadPicture Function	Returns a picture object. Available only on 32-bit platforms.
Log Function	Returns the natural logarithm of a number.
LTrim Function	Returns a copy of a string without leading spaces.
Mid Function	Returns a specified number of characters from a string.
Minute Function	Returns a whole number between 0 and 59, inclusive, representing the minute of the hour.
Month Function	Returns a whole number between 1 and 12, inclusive, representing the month of the year.
MonthName Function	Returns a string indicating the specified month.
MsgBox Function	Displays a message in a dialog box, waits for the user to click a button, and returns a value indicating which button the user clicked.
Now Function	Returns the current date and time according to the setting of your computer's system date and time.
Oct Function	Returns a string representing the octal value of a number.
Replace Function	Returns a string in which a specified substring has been replaced with another substring a specified number of times.
RGB Function	Returns a whole number representing an RGB color value.
Right Function	Returns a specified number of characters from the right side of a string.
Rnd Function	Returns a random number.
Round Function	Returns a number rounded to a specified number of decimal places.
RTrim Function	Returns a copy of a string without trailing spaces.
ScriptEngine Function	Returns a string representing the scripting language in use.
ScriptEngineBuildVersion Function	Returns the build version number of the scripting engine in use.
ScriptEngineMajorVersion Function	Returns the major version number of the scripting engine in use.
ScriptEngineMinorVersion Function	Returns the minor version number of the scripting engine in use.
Second Function	Returns a whole number between 0 and 59, inclusive, representing the second of the minute.
SetLocale Function	Sets the global locale and returns the previous locale.
Sgn Function	Returns an integer indicating the sign of a number.
Sin Function	Returns the sine of an angle.
Space Function	Returns a string consisting of the specified number of spaces.
Split Function	Returns a zero-based, one-dimensional array containing a specified number of substrings.
Sqr Function	Returns the square root of a number.
StrComp Function	Returns a value indicating the result of a string comparison.
String Function	Returns a repeating character string of the length specified.
StrReverse Function	Returns a string in which the character order of a specified string is reversed.
Tan Function	Returns the tangent of an angle.
Time Function	Returns a Variant of subtype Date indicating the current system time.
Timer Function	Returns the number of seconds that have elapsed since 12:00 AM (midnight).
TimeSerial Function	Returns a Variant of subtype Date containing the time for a specific hour, minute, and second.
TimeValue Function	Returns a Variant of subtype Date containing the time.
Trim Function	Returns a copy of a string without leading or trailing spaces.
TypeName Function	Returns a string that provides Variant subtype information about a variable.
UBound Function	Returns the largest available subscript for the indicated dimension of an array.
UCase Function	Returns a string that has been converted to uppercase.
VarType Function	Returns a value indicating the subtype of a variable.
Weekday Function	Returns a whole number representing the day of the week.
WeekdayName Function	Returns a string indicating the specified day of the week.
Year Function	Returns a whole number representing the year.


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