How to Use Loops in VB6
Understanding how loops work in Visual Basic 6 (VB6) is important because it lets you execute blocks of code repeatedly. The two main types of loops are "for" and "do" loops. A "for" loop is a shorthand version of a "do" loop that is used when the number of iterations is known beforehand. Some uses of a loop are reading in lines from a file, printing everyone's name from an employee list and sorting through an array looking for a specific value.
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Instructions
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Open your source file in Visual Basic 6.
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Add a "for" loop by typing the following code in your function:
Dim X As Integer
Dim count As Integer
x = 0
For count = 1 To 6 Step 2
X = X + 2
Next
A "for" loop consists of a counter, the range of the counter, a step and the commands to execute during each iteration. The "step" argument sets how much the counter will increase between iterations. If you omit the "step" keyword it's set to the default value of 1. In the example, during the first iteration, "count" is equal to 1 and "X" is set to 2 (0+2). On the second iteration "count" is set to 3 and "X" is set to 4 (2+2).
If you want to loop through a list instead, add the following code:
Dim MyColors(2) as String
Dim color as String
MyColors(0) = "Blue"
MyColors(1) = "Green"
MyColors(2) = "Yellow"
For Each color In MyColors
Debug.Print color
Next
The loop iterates for each value in the list, which is typically an array or collection. The iterating variable, "color," must be of the same type as the elements in the list.
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Add a "do" loop by typing the following code:
Dim X as Integer
x = 0
Do While X < 10
X = X + 2
Loop
The loop keeps iterating while the condition after the "Do" keyword is met. The condition is checked at the beginning before each new iteration. Alternatively, you can set it to iterate until a condition is met by adding the following code:
Do
X = X + 2
Loop Until X > 10
In a "loop until" structure the condition is checked after the end of each iteration. If you want to exit the loop before the condition is met, add "Exit Do" inside your loop.
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Save the VB6 file, compile and run the program to view your loop.
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