The looping statements are used to repeat a block of code for a predetermined number of times. There are 4 statements to do so:
1) For ... Next - the code is run a number of times;
2) For Each ... Next - the code is run for each item in a collection;
3) Do ... Loop - the code is run until a condition is met;
4) While ... Wend - the same as Do ... Loop.
For ... Next
As said, the statement is used to run a block of code a specified number of times. The For determines the starting and ending of the loop, while Next increments the variable (i) by one.
<%
For i = 0 to 5
response.write ("Count: " & i & "<br>")
Next
%>
Using the Step keyword, we can determine the value by which the variable (i) is incremented. In the following example we increment it by 3:
<%
For i = 0 to 10 Step 3
response.write ("Count: " & i & "<br>")
Next
%>
You can even use negative numbers for the Step keyword: remember though that the loop should be someway reversed:
<%
For i = 10 to 1 Step -1
response.write ("Count: " & i & "<br>")
Next
%>
You can even use an Exit point in the looping:
<%
For i = 0 to 12
if i = 5 then Exit For
response.write ("Count: " & i & "<br>")
Next
%>
For Each ... Next
Using the For Each, lets you loop through a collection:
<%
Dim fruits(3)
fruits(0) = "Apples"
fruits(1) = "Bananas"
fruits(2) = "Oranges"
fruits(3) = "Pears"
For Each x in fruits
response.write (x & "<br>")
Next
%>
Do ... Loop
If we don't know the number of loops, before running the statement, we can use the Do ... Loop. The code is run until a condition is met or while a condition is true.With the While keyword, every time the loop is closed we check a condition.
<%
Do While i > 10
some code
Loop
%>
The code inside the loop is executed only when i is greater than 10.
<%
Do
some code
Loop While i > 10
%>
The code inside the loop is executed at least one time, even if i is less than 10.If we use the Until keyword, the code is executed until a condition is met.
<%
Do Until i = 10
some code
Loop
%>
The code is executed unless i is equal to 10.
<%
Do
some code
Loop Until i = 10
%>
The code is executed at least one time, even if i is equal to 10.We can exit the loop with Exit Do.
<%
Do Until i = 10
i = i -1
If i < 10 then Exit Do
Loop
%>
The code is executed until i is different from 10, and as long as i is greater than 10.
While ... Wend
The statement is used mainly in repeat region.
<%
While NOT RS.EOF
some code
Wend
%>
And that is all. Hope you find this short article useful!
No comments:
Post a Comment
Comments are moderated. I apologize if I don't publish comments immediately.
However, I do answer to all the comments.