VBScript Conditional Statements
Conditional Statements
Conditional statements are used to perform different actions for different decisions.
In VBScript we have four conditional statements:
- if statement - executes a set of code when a condition is true
- if...then...else statement - select one of two sets of lines to execute
- if...then...elseif statement - select one of many sets of lines to execute
- select case statement - select one of many sets of lines to execute
If....Then.....Else
Use the If...Then...Else statement if you want to
- execute some code if a condition is true
- select one of two blocks of code to execute
If you want to execute only one statement when a condition is true, you can write the code on one line:
| if i=10 Then msgbox "Hello" |
There is no ..else.. in this syntax. You just tell the code to
perform one action if a condition is true (in this case if i=10).
If you want to execute more than one statement when a condition is true,
you must put each statement on separate lines, and end the statement with the
keyword "End If":
if i=10 Then
msgbox "Hello"
i = i+1
end If |
There is no ..else.. in the example above either. You just tell the code to perform multiple actions if the condition is true.
If you want to execute a statement if a condition is true and execute another statement if the condition is not true, you must add the "Else"
keyword:
Example (IE Only)
<html>
<body>
<script type="text/vbscript">
function greeting()
i=hour(time)
if i < 10 then
document.write("Good morning!")
else
document.write("Have a nice day!")
end if
end function
</script>
</head>
<body onload="greeting()">
</body>
</html> |
|
In the example above, the first block of code will be executed if the condition is true, and the other block
will be executed otherwise (if i is greater than 10).
If....Then.....Elseif
You can use the if...then...elseif statement if you want to select one of many blocks of
code to execute:
Example (IE Only)
<html>
<body>
<script type="text/vbscript">
function greeting()
i=hour(time)
If i = 10 then
document.write("Just started...!")
elseif i = 11 then
document.write("Hungry!")
elseif i = 12 then
document.write("Ah, lunch-time!")
elseif i = 16 then
document.write("Time to go home!")
else
document.write("Unknown")
end if
end function
</script>
</head>
<body onload="greeting()">
</body>
</html> |
|
Select Case
You can also use the SELECT statement if you want to select one of many blocks of
code to execute:
Example (IE Only)
<html>
<body>
<script type="text/vbscript">
d=weekday(date)
select case d
case 1
document.write("Sleepy Sunday")
case 2
document.write("Monday again!")
case 3
document.write("Just Tuesday!")
case 4
document.write("Wednesday!")
case 5
document.write("Thursday...")
case 6
document.write("Finally Friday!")
case else
document.write("Super Saturday!!!!")
end select
</script>
</body>
</html> |
|
This is how it works: First we have a single expression (most often a
variable), that is evaluated once. The value of the expression is then compared with the
values for each Case in the structure. If there is a match, the block of code
associated with that Case is executed.
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