C++ dll 将 object 返回到 Excel/VBA

Question

VS2019，办公室 16

如何从 C++ Z5884E40D596370BE5406F2711AD9E 返回自定义 object 到 Excel？

我的目标是从 Excel 调用 C++ function A。 在 function A 中，它将返回一个自定义 object 给 Excel。 我们可以将 object 作为参数放入 C++ function B 中。

如果 C++ ZC1C425268E68384FDC1AB45A 返回 7417A 我想要做的是返回一个自定义 object 而不是双精度。

我跟着这个网站打电话给C++ function。

header 文件

#pragma once
struct customObj
{
    double dbl = 3;
    customObj() {};
};

//Test function
double _stdcall square(double* x);
double _stdcall sqRoot(double* x);
double _stdcall getObj(customObj* a,double* x);
double _stdcall displayObj(const customObj& a);

.cpp 文件

#include "QLcpp.h"
#include <math.h>

double _stdcall square(double* x) {
    return *x * *x;
}

double _stdcall sqRoot(double* x) {
    return sqrt(*x);
}

double _stdcall getObj(customObj* a,double* x){
    customObj b;
    a = &b;
    *x = 100.;
    return 2;
};
double _stdcall displayObj(const customObj& a) {
    return a.dbl;
};

定义文件

LIBRARY "square"
EXPORTS
sq4EXL = square
sqrt4EXL = sqRoot
getObj4EXL = getObj
displayObj4EXL = displayObj

Excel

Private Declare PtrSafe Function sq4EXL Lib PATH2DLL (ByRef x As Double) As Double
Private Declare PtrSafe Function sqrt4EXL Lib PATH2DLL (ByRef x As Double) As Double
Private Declare PtrSafe Function getObj4EXL Lib PATH2DLL (ByRef rng As Variant, ByRef x As Double) As Double
Private Declare PtrSafe Function displayObj4EXL Lib PATH2DLL (ByRef rng As Variant) As Double

Public Function sqCpp(dArg As Double) As Double
    sqCpp = sq4EXL(dArg)
End Function

Public Function sqrtCpp(dArg As Double) As Double
    sqrtCpp = sqrt4EXL(dArg)
End Function

Public Function displayObj(ByVal rng As Variant) As Double
    displayObj = displayObj4EXL(rng)
End Function

Public Function getObj(ByVal rng As Variant) As Variant
    Dim obj As Object
    Dim i As Integer, x As Double
    i = getObj4EXL(obj, x)
    getObj = obj
End Function

在 VBA getObj中，如果我在getObj = obj行设置断点，变量i为 2， x为 100。 但是，变量obj是Nothing 。