Is there a built-in way to multiply every member of an array by some number in-place?
Example:
Dim volts () as Double = {1.243, 0.534, 5.343, 2.223, 4.334}
Dim millivolts (4) as Double = volts.MultiplyEachBy(1000) 'something like this
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what version of .net framework are you using?Andrew– Andrew2010-02-23 16:43:17 +00:00Commented Feb 23, 2010 at 16:43
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3 Answers
You can use the Array.ConvertAll method.
Array.ConvertAll(volts, Function(x) x * 1000)
EDIT
There is a small error in the sample code which needs to be corrected for the above to compile. Remove the explicit size (4) from the variable type
Dim volts() As Double = {1.243, 0.534, 5.343, 2.223, 4.334}
1 Comment
JaredPar
@Steven, there is a slight error in how you are declaring the variable volts. You need to remove the explicit size 4
I don't think there is a built in way to do this, but the best thing I could think to do would be to just create your own method. Something like
Public Function convertMilliamps(ByVal voltArray() As Double)
For Each item AS Double In voltArray
item = item * 1000
Next
Return voltArray()
End Function
then just do volts = convertMilliamps(volts)
Comments
Your function doesn't work for each item because an item is a copy of the value, not the actual item from the array. This should work:
Public Function MultiplyArrayByScalar(ByRef arry As Double(), ByVal scaler As Double) As Double()
Dim newArry As Double()
Dim size As Integer = arry.GetLength(0)
ReDim newArry(size - 1)
Dim i As Integer
For i = 0 To size - 1
newArry(i) = arry(i) * scaler
Next
Return newArry
End Function
