Conditional structures for VBScript

[Kohlmann]

Let us now insert some fork in the programs to perform operations under certain conditions the main command is IF. The syntax is as follows:

Then if <condition> 
<operations if the condition and true> 
Else 
<operations if the condition and false> 
End If

The following example uses the Month function () which returns the numeric month, and Now () which returns the current date and time:

<script language="VBScript"> 
<! - 
if month (Now ()) = 6 then 
document.write "and June" 
end if 
//--> 
</ Script>

If this is the month of June, will print "is June". To complete the program:

<script language="VBScript"> 
<! - 
if month (Now ()) = 6 then 
document.write "and June" 
else 
document.write "It's June" 
end if 
//--> 
</ Script>

You can also create structures within other structures or nested structures:

<script language="VBScript"> 
<! - 
if month (6 ())<= Now then 
document.write "We are in the first half of <br> 
if month (Now ())<= 3 then 
document.write "and the first quarter." 
else 
document.write "and in the second quarter." 
end if 
else 
document.write "We are in the second half of <br> 
if month (9 ())<= Now then 
document.write "and in the third quarter." 
else 
document.write "and in the fourth quarter." 
end if 
end if 
//--> 
</ Script>

Note the importance of a type of formatting "indent" (ie indentations) when using such complex structures.

[X-Ray]

Another use the IF statement is to give the most possible conditions:

<script language="VBScript"> 
<! - 
if month (Now ())<= 3 then 
document.write "We are in the first quarter." 
elseif month (6 ())<= Now then 
document.write "We are in the second quarter." 
elseif month (9 ())<= Now then 
document.write "We are in the third quarter." 
else 
document.write "We are in the fourth quarter." 
end if 
//--> 
</ Script>

Note that in this type of structure only a transaction is executed. Starting from the top down, the first true condition is executed the corresponding operation and exit the structure. In fact if we were in January would be all the conditions but would be printed only the first sentence. In the conditions you can use logical operators NOT, AND and OR to combine terms. When using structures with many choices depend on the value of a parameter, you can use the SELECT structure.

[DllD]

That's the same program with the structure of the first SELECT:

<script language="VBScript"> 
<! - 
Select Case Month (Now ()) 
houses 1,2,3 
document.write "We are in the first quarter." 
houses 4,5,6 
document.write "We are in the second quarter." 
houses 7,8,9 
document.write "We are in the third quarter." 
Case Else 
document.write "We are in the fourth quarter." 
End Select 
//--> 
</ Script>

In this structure, you define the variable to be controlled with the statement "Select Case Variable", and are then lists the possible values that can take the variable with the statement "case value1, value2, value3" to follow these directions what to do. In the example the variable is numeric, if the string variable the values are put between quotation marks:

case "value1", "value2", "value3"

[Ackley]

You should also know about the cycles which are related to the conditional structures. A cycle is simply to repeat the operations for a number of times, or until a certain condition does not occur. The for loop - NEXT increases with each cycle a variable. When this variable will come to a set value, the cycle will end.

<script language="VBScript"> 
<! - 
Option Explicit 
Dim i 
For i = 4 to 20 
document.write i & "<br> 
next 
//--> 
</ Script>

This program prints the values from 4 to 20 columns. Through the step, I can also count on the contrary, and with several steps:

<script language="VBScript"> 
<! - 
Option Explicit 
Dim i 
For i = 20 to 4 step -2 
document.write i & "<br> 
next 
//--> 
</ Script>

This program will display in numbers 20, 18, 16, 14, 12, 10, 8, 6, 4.