FreeBasic While/Wend Keywords

last modified June 16, 2025

The FreeBasic While and Wend keywords create a loop that executes as long as a condition remains true. This is a fundamental control structure for repetitive tasks in programming.

Basic Definition

In FreeBasic, While starts a loop that continues executing the code block between While and Wend while the condition is true. The condition is checked before each iteration.

The Wend keyword marks the end of the loop block. It's important to ensure the loop condition eventually becomes false to prevent infinite loops.

Simple While Loop

This example demonstrates a basic While loop that counts from 1 to 5.

while_simple.bas

Dim counter As Integer = 1

While counter <= 5
    Print "Count: "; counter
    counter += 1
Wend

Print "Loop finished"

The loop starts with counter at 1. Each iteration prints the current value and increments counter. When counter reaches 6, the condition becomes false and the loop exits. The message after Wend confirms loop completion.

While Loop with User Input

This example uses While to repeatedly prompt for input until valid.

while_input.bas

Dim age As Integer = 0

While age <= 0
    Input "Enter your age (positive number): ", age
Wend

Print "Thank you! Your age is: "; age

The loop continues until the user enters a positive number. The condition checks if age is less than or equal to zero. Invalid inputs keep the loop running, while valid input exits it.

Nested While Loops

While loops can be nested to handle more complex repetition patterns.

while_nested.bas

Dim i As Integer = 1
Dim j As Integer

While i <= 3
    j = 1
    While j <= 3
        Print "i:"; i; " j:"; j
        j += 1
    Wend
    i += 1
Wend

This creates a 3x3 grid of coordinates. The outer loop runs 3 times, and for each outer iteration, the inner loop runs 3 times. Each Wend matches its corresponding While, maintaining proper nesting structure.

While Loop with Early Exit

The Exit While statement allows premature loop termination.

while_exit.bas

Dim num As Integer = 1
Dim sum As Integer = 0

While True
    sum += num
    num += 1
    
    If sum > 20 Then
        Exit While
    End If
    
    Print "Current sum:"; sum
Wend

Print "Final sum:"; sum

This loop would run forever due to the True condition, but the Exit While statement stops it when sum exceeds 20. This pattern is useful when the exit condition is complex or occurs mid-loop.

While Loop with Boolean Flag

A Boolean variable can control loop execution for more readable code.

while_flag.bas

Dim keepRunning As Boolean = True
Dim attempts As Integer = 0

While keepRunning
    attempts += 1
    Print "Attempt:"; attempts
    
    If attempts >= 5 Then
        keepRunning = False
    End If
Wend

Print "Finished after"; attempts; "attempts"

The Boolean flag keepRunning controls the loop. After 5 attempts, we set it to False to exit. This approach makes the loop's purpose clearer than embedding the condition directly in the While statement.

While Loop with Array Processing

While loops are effective for processing arrays when the size is unknown.

while_array.bas

Dim numbers(10) As Integer
Dim i As Integer = 0

' Fill array with random numbers
While i < 10
    numbers(i) = Int(Rnd * 100) + 1
    i += 1
Wend

i = 0
Dim total As Integer = 0

' Calculate sum
While i < 10
    total += numbers(i)
    i += 1
Wend

Print "Array sum:"; total

The first While loop fills an array with random numbers. The second While loop calculates their sum. Both loops use the same counter pattern but perform different operations on the array elements.

While Loop with String Processing

This example processes a string character by character using a While loop.

while_string.bas

Dim text As String = "FreeBasic"
Dim index As Integer = 1
Dim uppercaseCount As Integer = 0

While index <= Len(text)
    Dim c As String = Mid(text, index, 1)
    
    If c >= "A" And c <= "Z" Then
        uppercaseCount += 1
    End If
    
    index += 1
Wend

Print "Uppercase letters in '"; text; "':"; uppercaseCount

The loop examines each character in the string, counting uppercase letters. The condition uses Len(text) to determine when to stop. String indexing starts at 1 in FreeBasic, so we initialize index to 1.

Best Practices

Initialization: Always initialize loop control variables before the While.
Termination: Ensure the loop condition will eventually become false.
Bracketing: Use consistent indentation between While and Wend.
Complex conditions: For complex conditions, use Boolean variables.
Comments: Add comments for non-obvious loop conditions or exits.

This tutorial covered the FreeBasic While/Wend keywords with practical examples showing their usage in different scenarios.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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