VBC09371 — Array argument must be ByRef

Severity: Error · Family: VBC (static semantics / abstract syntax tree) · Source metadata: VBCompileErrorInfo

An array parameter is declared ByVal, or an argument of one is written ByVal.

An array parameter (a() As Long) is always ByRef: the procedure is given the array itself, never a copy of it, so an array cannot be passed by value. ByVal written in its declaration, or before its argument, asks for what the parameter cannot be.

MS-VBA reports the same error, with the same message (recorded in Excel).

This code is raised where the declarations of a module are checked, at the parameter declared ByVal, and where a call is checked, at the argument written ByVal.

How it is raised

Situation	Example	Resolution
An array parameter declared `ByVal`: of a procedure, a property, an event, a `Declare`, or an implementation of an interface's member.	`Sub Bump(ByVal a() As Long)`	Remove `ByVal`: `Sub Bump(a() As Long)`. To work on a copy, copy the array in the procedure.
An array given `ByVal` to an array parameter.	`Sub Bump(a() As Long)` … `Bump ByVal values`	Remove `ByVal`: the procedure works on the array. To work on a copy, copy it first: `Dim copy() As Long: copy = values`.

Table of Contents

VBC09371 — Array argument must be ByRef

How it is raised

See also