How can I receive the multi return values from DLL in VBA(Excel Visual Basic)?

Now, I'm currently trying to receive the multiple return value from DLL in VBA(Excel Visual Basic).

This is my DLL code.

        double _stdcall pll_dll(double* datain0, double* datain1, double* dataout0, double* dataout1)
    {
    	dataout0[0] = datain0[0]+10;
    	dataout1[0] = datain1[0]+10;
    
    	return 0;
    }

Then I want to give some value to the DLL by using the datain0 and datain1 and receive the dataout0 and dataout1 from the DLL in the VBA(Excel Visual Basic).

This is my VBA code.actually, I'm not familiar with VBA(Excel Visual Basic)

    Option Explicit
    
    
    Private Declare PtrSafe Function pll_dll Lib "F:\work\pll_dll\x64\Debug\pll_dll.dll" (ByRef x_in As Double, ByRef y_in As Double, ByRef x_out As Double, ByRef y_out As Double) As Double
    Dim Error As Integer
    Dim dat0 As Double
    Dim dat1 As Double
    Dim dat2 As Double
    Dim dat3 As Double
    
      
    Function pll_dll_excel(data0 As Double, data1 As Double, data2 As Double, data3 As Double) As Double
    
          pll_dll_excel = pll_dll(data0, data1, data2, data3)
    End Function
    
    
    Sub useSquareInVBA()
       MsgBox pll_dll_excel(3, 4, Cells(5, 5), Cells(6, 6))
    End Sub

What am I supposed to make the function which is what I want to give datain0=3, datain1=4 and receive the dataout0 and dataout1 values?
If I run the above code in the excel, I've got a problem halt

Your dll function is modifying the variables passed to it using ByRef (data2 and data3) so your function pll_dll_excel should return those values as an array instead of passing the returned 0 from the dll. This is how you should be using the ByRef variables - I have just created a fake pll_dll function for demonstration.... when you pass Cells() you are only passing the value and not the cell object so you cannot write directly to it.

Option Explicit
Function pll_dll(ByRef datain0 As Double, ByRef datain1 As Double, ByRef dataout0 As Double, ByRef dataout1 As Double) As Boolean
    dataout0 = datain0 + 10
    dataout1 = datain1 + 10
    pll_dll = True
End Function

Function pll_dll_excel(data0 As Double, data1 As Double) As Variant
    Dim data2 As Double
    Dim data3 As Double
    Dim ret As Boolean
    
    ret = pll_dll(data0, data1, data2, data3)
    
    If ret Then
        pll_dll_excel = Array(data2, data3)
    Else
        pll_dll_excel = xlErrNull
    End If
End Function


Sub useSquareInVBA()
    Dim v As Variant
    
    v = pll_dll_excel(3, 4)
    
    If Not v = xlErrNull Then
        Cells(5, 5).Value = v(0)
        Cells(6, 6).Value = v(1)
    Else
        MsgBox "oops"
    End If
    
End Sub

Originally Posted by Bernie Deitrick

Your dll function is modifying the variables passed to it using ByRef (data2 and data3) so your function pll_dll_excel should return those values as an array instead of passing the returned 0 from the dll. This is how you should be using the ByRef variables - I have just created a fake pll_dll function for demonstration.... when you pass Cells() you are only passing the value and not the cell object so you cannot write directly to it.

[CODE]Option Explicit
Function pll_dll(ByRef datain0 As Double, ByRef datain1 As Double, ByRef dataout0 As Double, ByRef dataout1 As Double) As Boolean
dataout0 = datain0 + 10
dataout1 = datain1 + 10
pll_dll = True
End Function

Function pll_dll_excel(data0 As Double, data1 As Double) As Variant
Dim data2 As Double
Dim data3 As Double
Dim ret As Boolean

ret = pll_dll(data0, data1, data2, data3)

If ret Then
pll_dll_excel = Array(data2, data3)
Else
pll_dll_excel = xlErrNull
End If
End Function


Sub useSquareInVBA()
Dim v As Variant

v = pll_dll_excel(3, 4)

If Not v = xlErrNull Then
Cells(5, 5).Value = v(0)
Cells(6, 6).Value = v(1)
Else
MsgBox "oops"
End If

End Sub
[JCODE]

Dear bernie,

I've just modified as the below.

Function pll_dll_excel(data1 As Double, data2 As Double,   data3 As Double, data4 As Double) As Double 
 pll_dll_excel = pll_dll(data1, data2, data3, data4) 
End

Function Sub useSquareInVBA() 
 MsgBox pll_dll_excel(3, 4, d1, d2)
 Cells(5, 5).Value = d1
 Cells(6, 6).Value = d2 
End Sub

Is this correct?

No.

You cannot have a Function Sub ("Function Sub useSquareInVBA() ")

Try just using the dll function directly - your dll already uses ByRef:

Function Sub useSquareInVBA() 
   Dim v As Variant
   v = pll_dll(3, 4, d1, d2)
   Cells(5, 5).Value = d1
   Cells(6, 6).Value = d2 
End Sub

Have you updated your declaration line?

    Private Declare PtrSafe Function pll_dll Lib "F:\work\pll_dll\x64\Debug\pll_dll.dll" (ByRef x_in As Double, ByRef y_in As Double, ByRef x_out As Double, ByRef y_out As Double) As Double

Originally Posted by Bernie Deitrick

Have you updated your declaration line?

    Private Declare PtrSafe Function pll_dll Lib "F:\work\pll_dll\x64\Debug\pll_dll.dll" (ByRef x_in As Double, ByRef y_in As Double, ByRef x_out As Double, ByRef y_out As Double) As Double

Dear Bernie,
This is my C code
q8.JPG

ans the below code is the VBA code

Option Explicit

Private Declare PtrSafe Function pll_dll Lib "C:\Users\carter\Downloads\pll_dll\pll_dll\x64\Debug\pll_dll.dll" _
(ByRef x_in As Double, ByRef y_in As Double, ByRef x_out As Double, ByRef y_out As Double, ByVal str As String) As Double

Dim Error As Integer

Dim d1 As Double
Dim d2 As Double
Dim d3 As Double
Dim d4 As Double
Dim sometext As String
Dim str As String


Function pll_dll_excel(data1 As Double, data2 As Double, data3 As Double, data4 As Double, ByRef text As String) As Double

pll_dll_excel = pll_dll(data1, data2, data3, data4, text)
    
End Function






Sub useSquareInVBA()
    MsgBox pll_dll_excel(3, 4, d1, d2, sometext)
    Cells(5, 5).Value = d1
    Cells(6, 6).Value = d2
    Cells(7, 7).Value = sometext
End Sub

The problem is that I can get the any string data from dll.
Would you please help me please?

Change

 ByVal str As String

Private Declare PtrSafe Function pll_dll Lib "C:\Users\carter\Downloads\pll_dll\pll_dll\x64\Debug\pll_dll.dll" _
(ByRef x_in As Double, ByRef y_in As Double, ByRef x_out As Double, ByRef y_out As Double, ByVal str As String) As Double

to

 ByRef str As String

Private Declare PtrSafe Function pll_dll Lib "C:\Users\carter\Downloads\pll_dll\pll_dll\x64\Debug\pll_dll.dll" _
(ByRef x_in As Double, ByRef y_in As Double, ByRef x_out As Double, ByRef y_out As Double, ByRef str As String) As Double

It might be an issue with C, but I don't know C - sorry. You might want to start a new thread.