Looping using the 'For' loop.

Seeing as I have just given an example of how to use the 'do while' loop, I may as well quickly give an example of how to use the 'for' loop. I will use the same example of needing to read in 10 numbers and then print out the sum.

Here is the program using the 'for' loop.

' ==================================
'  Demonstration Of The 'For' Loop
' ==================================
' Description:
' This program demonstrates the use of
' the 'for' loop to read in 10 numbers
' from the user.  The sum of the 10
' numbers is calculated and output at
' the end of the program.
'
' Author: Eddie Meyer
' Date: 24th May 2006

' Variables
' ============

' The number of items to read in
NumItemsToRead = 10

' The current total
Total = 0

' Loop until we have read in the required
' number of items.
for i = 1 to NumItemsToRead
    if i = 1 then
        input "Please enter a number: "; InputNumber
    else
        input "Please enter another number: "; InputNumber
    end if

    ' Update the current total
    Total = Total + InputNumber
next

' Print out the total
print
print "The sum of the "; NumItemsToRead; " numbers you entered is ";
print Total; "."

end

Points to note about the 'for' loop are...

1) The use of the 'for' and 'next' keywords.

2) The variable that will be used as the counter.

3) The start value of the counter and the end value of the counter.

As you can see, the 'for' loop is really simple to use and ideal for cases where you just want to iterate over a piece of code a certain number of times. It is pretty common practice to use simple variables names with for loops (like i in my example above). Normally, you are encouraged to use very descriptive names for your variables, but in the case of the 'for' loop, we know the variable is just going to be some kind of counter so we can make an exception here and keep it simple. I used a variable called i because this seems to have developed into the most commonly used variable name for 'for' loops. By sticking with convention, other programmers will find it easier to read and maintain my code (should they need to). Note: the letter 'i' can at least be seen to be an abbreviation of the word 'index'. :-).

There you go. You have now officially been introduced to the three main types of loops provided by Liberty Basic.

Have fun with your programming.

Eddie