vbscriptstatements

VBScript Statements: Explanation of the Execute Statement

The VBScript Execute statement allows you to execute a series of VBScript statements as a block from within a VBScript Script. By itself it doesn’t sound terribly appealing… after all, Executing a series of VBScript statements is what you do inside a VBScript file.

However, if you consider that you can load the statements from another file, it becomes somewhat interesting because it could allow you to share code between scripts or add funtionality like some applications that allow scripting inside the application.

The syntax of the Execute Statement is simply as follows:

Execute statement

Statement can be a series of commands enclosed in quotes, with each command separated with a colon (:) or a variable that contains a string that is the commands you wish to execute.

For More information on this statement, check out Microsoft’s documentation here.

VBScript Statements: Explanation of the Rem Statement

The VBScript REM statement is used to place a comment in your script or function. It is typically considered essential to place comments in code, not only to document what something does for others– but for yourself 6 months down the line.

 Another short hand method of placing a comment in the code is to use the ‘ character to comment the code. Below are two examples:

 Rem This is a comment
‘ This is a comment too
x=x+1 ‘this is a comment after a line of code, the code is processed and the comment is ignored.

VBScript Statements: Explanation of the For Each … Next Statement

The For Each Next statement combination is very useful for situations where you need to loop through a piece of code a specific number of times, just like the For Next statement, except that you may not even know at run time how many items you need to loop through. 

This particular variation of the For Next statement is particularly helpful when iterating through arrays, objects, or collections– cases where you may not know how many items are in the object or collection with out going through them first. (Which would be a waste of resources)
 
You can use Exit For statements to exit out of a For Each Next loop, if you need to check for a condition inside the loop.

Here is an example of a For Each Next statement:

ReDim Collection(2)
Collection(0) = “Test”
Collection(1) = “Test 2″
Collection(2) = “Test 3″

For Each Item in Collection
     wscript.echo item
next

VBScript Statements: Explanation of the For … Next Statement

The For Next statement is very useful for situations where you need to loop through a piece of code a specific number of times. 
 
You can use Exit For statements to exit out of a For loop, if you need to check for a condition inside the loop. Additionally, The Step keyword at the end of the line that has the for statement will allow you to loop through a For statement in any size of increment. 

Here is an example of a for statement, followed by one with a Step key word:

For x = 1 to 10
     wscript.echo x
next

For x=1 to 20 step 2
    wscript.echo x
next
 

VBScript Statements: Explanation of the Erase statement

The VBScript Erase statement is used to erase all the values of an array, but keep the array size and dimensions intact.

 This is useful when you re-use an array and you want to ensure the values inside an array have truely been cleared and no old data is left in the array.

For example, the following would print a blank line:

Redim Bob(10)
Bob(1) = “Rickky Bobby”
Erase Bob
Wscript.echo Bob(1)

VBScript Statements: Explanation of the Exit statement

The Exit statement in vbscript allows you to exit a block of code, in the case of a subroutine (Exit Sub) or a function (Exit Function), or the entire script.

This statement is assumed at the end of a script, and therefore is not required, but is typically used in conditional statements to exit a section of code when a particular condition is met.

 Below is an example:

 mysub(1)
 mysub(3)
 mysub(2)
 mysub(0)

sub mysub(testvar)
    testvar=testvar + 1
    if testvar =2 then
        exit sub
    else
        wscript.echo testvar
    endif
end sub

VBScript Statements: Explanation of the Do Loop Statement

The Do … Loop statement is very useful (like, for … next and Select … case) to execute a block of code more than once. However, where it differs from the other two is that the Do … Loop statement executes the code as long as (while) a condition is true or until a condition becomes true.

Typical uses of a Do … Loop are in cases where you may not know how many times you need to execute the code section because it could vary from situation to situation, like when reading in a file or taking in keyboard input.

In this example of a Do While Loop, we check to see if a variable is less than 10 and if not continue to run the code in the loop. (Notice how when x = 10 the code does not run and at the end x =10?)

x = 0
Do While x> 10
Wscript.Echo(”X = ” & x)
x= x + 1
Loop
Wscript.Echo(”X is now ” & x)

In this example of a Do Until Loop, we check to see if a variable is greater than 10, but use the until condition to run the loop. (Notice how when X = 10 the code does run and at the end x=11?)

x = 0
Do Until x > 10
Wscript.Wcho(”X = ” & x)
x= x + 1
Loop
Wscript.Echo(”X is now ” & x)

VBScript Statements: Explanation of the Option Explicit Statement

In VBScript declaring your variables up front is not required (as stated in this sites explanation of the Dim Statement), however, many programmers choose to declare their variables up front to avoid having to track down misspellings in their code. They go further by adding the Option Explicit statement to force them to do so. With Option Explicit turned on and error is thrown when a variable is used before being declared.

Consider the following code, that doesn’t use Option Explicit:

TheFirstVariable = 1
TheSecondVariable = 2
TheThirdVariable = TehFirstVariable + TheSecondVariable

Wscript.echo TheThirdVariable

The output will be 2, when you were expecting 3! To find the error, if you didn’t notice it, read the third line very slowly TheFirstVariable is spelled differently as TehFirstVariable– therefore creating a new variable with a default value of zero. (or empty if used as a string)

VBScript Statements: Explanation of the Dim Statement

The DIM statement is used to declare variables prior to being used. To save space in your code, you can declare more than one variable in a single statement by separating each variable with a comma.

For example:

Dim x
Dim x, y, z

The Dim statement is not required in VBScript because VBScript will automatically create variables at the time you first use them.

VBScript Statements: Explanation of the Const Statement

The Const statement is useful when you want to reference a specific, unchanging, value in your code multiple times without typing it over and over.

For example, in order to use the Const Statement to create a reference to the value of pi to 50 decimal places, you use the following code:

Const pi = 3.14159265358979323846264338327950288419716939937510

The important thing to remember is that, constants can not be changed once set in your code– Doing so will result in an error being thrown.