使用C ++中创建的DLL从Excel和VBA调用C ++函数 [英] Calling C++ function from Excel and VBA using DLL created in C++

问题描述

我创建了一个包含名为koduj的函数的DLL。通过在Excel工作表单元格中使用此函数来调用此函数，将返回所需的结果。从VBA调用koduj返回错误的答案。

I created a DLL containing a function named "koduj". Calling this function by using it inside an Excel worksheet cell returns the desired result. Calling "koduj" from VBA returns wrong answer.

koduj需要两个参数：string nr_id和整数x1。它计算ASCII表示中nr_id的字母的总和，并添加x1。

koduj needs two arguments: string nr_id and integer x1. It calculates sum of nr_id's letters in ASCII representation and adds x1. Calculated sum is than returned.

我按照以下指示找到此处

这是我的.cpp源文件：

Here's my .cpp sourcefile:

#include<Windows.h>
#include<string>
using namespace std;


//Convert BSTR to wstring for convenience
wstring BSTR_to_wstring (BSTR text){
    return wstring(text, SysStringLen(text));
}

//Calculate sum of letters in ASCII representation
int ASCII_sum (wstring ws){
    int sum = 0;
    for (unsigned int i = 0; i < ws.length(); i++)
        sum += ws[i];
    return sum;
}

//"koduj" function
int _stdcall koduj (BSTR nr_id, int & x1){
    wstring ws_nr_id = BSTR_to_wstring(nr_id);
    return ASCII_sum(ws_nr_id) + x1;
}

这是我的VBA函数声明：

Here's my VBA function declaration:

Declare Function koduj _
Lib "<dll_directory_and_full_name>" (ByVal x As String, ByRef y As Integer) As Integer

写：

=koduj("aaa";1)

在工作表单元格中获取所需的结果（292）

Inside a worksheet cell I get desired result (292)

调试此VBA代码：

Sub test()

Dim a As Integer
a = koduj("aaa", 1)

End Sub

显示错误的结果（a = 24930）

reveals wrong result (a = 24930)

我相信我的C ++代码是好的，因为它从Excel的工作表调用时正常工作。

I belive my C++ code is fine, as it works properly when called from Excel's worksheet.

推荐答案

从错误的大小，它是数值参数的错误 - 我会尝试更明确地声明测试VBA例程（可能是Integer）中的参数类型，并接受它作为C ++侧的特定类型（签名短，在

I'm guessing from the magnitude of the error that it's the numeric parameter that's going wrong - I would try more explicitly declaring the parameter type in your test VBA routine (probably Integer) and accepting it as that specific type on the C++ side (signed short, in that case).

有关这一切的一篇很好的Microsoft文章 http://msdn.microsoft.com/en-us/library/office/bb687915（v = office.15）.aspx 。

There's a great Microsoft article about all this at http://msdn.microsoft.com/en-us/library/office/bb687915(v=office.15).aspx.

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