VB.NET ParamArray (Use varargs Functions)

Use the ParamArray keyword to accept a variable number of arguments to a method.

ParamArray. This keyword allows a method to be called with an array of values that are specified directly (not in an explicit array). The values are placed into an array by the compiler.Array

For optimal performance, adding many overloaded methods is usually best. But ParamArray can be used in VB.NET programs where performance is not that important.

An example program. Let us examine a simple program that uses ParamArray. Notice how the ParamArray keyword comes first, then the array name with parentheses attached to it.

Here: PrintValues receives a ParamArray. We can call it with zero, one or many arguments.

Warning: For performance, avoiding ParamArray is often a better solution. An array is created for each call to a ParamArray method.

VB.NET program that uses ParamArray argument Module Module1 Sub PrintValues(ParamArray values() As Integer) ' Display Length of array. Console.WriteLine("Count: " + values.Length.ToString()) ' Loop over ParamArray values. For Each value As Integer In values Console.WriteLine(value) Next End Sub Sub Main() ' Use ParamArray method. PrintValues() PrintValues(1) PrintValues(10, 20, 30) End Sub End Module Output Count: 0 Count: 1 1 Count: 3 10 20 30

Some notes. Performance is not everything. For simplicity, using ParamArray for a varargs Function is a good plan. Often the array overhead will not matter.Function

A review. ParamArray is the same construct as "params" in C#. Other languages have similar constructs, sometimes referred to as varargs for "variadic" or "variable" argument lists.
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