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Visual Basic .NET / Procedures

ByRef

Learn ByRef in Visual Basic .NET through a focused explanation, a dedicated construct-specific example, an engineering boundary, and a mastery check.

10 min read • Beginner

ByRef is an atomic Visual Basic .NET topic inside Procedures. This lesson focuses on how the ByRef construct is written, what it changes, and when it is the right tool.

Trace the example line by line. Identify the exact syntax for ByRef, the input state before it runs, and the resulting value, control flow, database state, hardware behavior, or runtime effect afterward. Neighboring lessons use different constructs rather than renamed copies of this one.

Topic-specific example

vbnet-03-04-byref.vb
vbnet Try It Live 
Sub Increment(ByRef n As Integer)
    n+=1
End Sub
Dim x=5
Increment(x)
Console.WriteLine(x)
Edge case / engineering note

For ByRef, test the boundary that belongs to this exact feature rather than a generic failure case. Check invalid or empty input, NULL/unknown state, numeric limits, transaction or exception behavior, synthesis/runtime constraints, ownership/permission rules, or backtracking/control-flow effects where they apply.

Content source & attribution
Original Syntaxis Content · Original Syntaxis Content

Lesson quizzes

ByRef Mastery Check →
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ByVal
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Optional parameter