How can I do a Calculation in Microsoft Excel VBA? - excel

Question

I'm 15 and I'm doing a Internship as a Developer and I've got a kinda hard exercise.
I have a Table with 3 columns, A is "Number" B is "percent" and C is "Value". The column "value" is blank and I Need to calculate the value with a macro button. I've tried this, but it was wrong because I didn´t calculate it in VBA:
Public Sub PushButton ()
Range("C2:C11").Formula = "=A2*B2/100"
Range("C2:C11").Value = Range("C1:C6).Value
End Sub
How do I solve this?

Answer 1

You are using a defined range, you could do it with a dynamic range like this:
Option Explicit
Sub PushButton()
Dim i As Long, LastRow As Long
With ThisWorkbook.ActiveSheet
LastRow = .Cells(.Rows.Count, 1).End(xlUp).Row 'first you need to find the last row on the active sheet
For i = 2 To LastRow 'then iterate through all the rows starting from 2, if row 1 has headers
.Cells(i, 3) = .Cells(i, 1) * .Cells(i, 2) / 100
Next i
End With
End Sub
If you need help understanding this code, let me know.
Edit: Explanation
Well, the first thing you must do is Dimension all your variables, and to help that you can use the Option Explicitright above all your code.
I've dimensioned 1 variable for the loop and another one to find the last row with text.
To find the last row what you are actually doing is going to excel, select the last row (1048576) and the column where it will have text, in this case 1 or column "A" and then pushing ctrl+Up excel and vba will get you to the last cell with text.
To do that you use Cells(Row, column) instead of manually inserting row 1048576 you can just use rows.count and it will be the same.
Once you get the last row you just iterate with a For iloop meaning For a variable called i which equals 2 (For i = 2) To LastRow (to the last row you calculated) VBA will repeat the code in between the ForAnd Next adding 1 number to i everytime the loop restarts.
In this case is just adding a number to the rows on Cells(i, 3) so you can modify that cell depending of its i value.

Answer 2

I think you need to question why Excel needs to calculate on demand rather than automatically like normal. Failing that there are a few options
You could change your calculation method to Manual using the following in the ThisWorkbook object
Option Explicit
Dim xlCalcMethod As XlCalculation
Private Sub Workbook_Open()
With Application
' Store users current method for when closing the workbook
xlCalcMethod = .Calculation
.Calculation = xlCalculationManual
End With
End Sub
Private Sub Workbook_BeforeClose(Cancel As Boolean)
' Reset calculation
Application.Calculation = xlCalcMethod
End Sub
and then when the button is pressed use the following code to calculate placed in a Module
Option Explicit
Public Sub Button_Click()
Application.Calculate
End Sub
Another option to do this without looping would be:
Sub CalculateRange()
Dim rng As Range
' Update for your Range
With ActiveSheet
Set rng = .Range("C2:C" & .Cells(.Rows.Count, "A").End(xlUp).Row)
End With
rng.Value2 = Evaluate(rng.Offset(0, -2).Address & "*" & rng.Offset(0, -1).Address & "/100")
End Sub
Finally, the way you've come up with is perfectly acceptable as VBA