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Introduction

I am referring to xlw, the Excel C API wrapper by Mark Joshi and others.

Before starting with my example, my trials and my question, a couple of words about how to reproduce these codes: once you've downloaded and installed xlw from its website, you should find a folder named XLL_Project, whose contents is a Visual Studio solution ("Template.sln") if this IDE/platform has been selected during installation; this solution is made of a cppinterface.h, that is, an header file which defines what functions should be present in your final .xll, and a source.cpp, which specifies how said functions should behave.

Code

Let an interface function like the following one is in cppinterface.h and its behavior is in source.cpp:

// ===== cppinterface.h =====

std::string // Asks the user to enter the number of pancakes eaten for breakfast by different people. Analyzes the data and output which person ate the most pancakes
    PancakeGlutton(const MyArray& people, // Range of people
                   const MyArray& pancakeNumber // Range of pancakes eaten by each person
                  );

// ===== source.pp =====

std::string PancakeGlutton(const MyArray& people, const MyArray& pancakeNumber)
{
    if (people.size() != pancakeNumber.size())
        throw("Error: arrays must have the same dimension!");
    std::map< std::string, int > myMap;
    for (unsigned long i = 0; i < people.size(); i++)
    {
        myMap.insert(std::pair< std::string, int >(people[i], pancakeNumber[i]));
    }
    return "x"; // Of course this a strange output just for the sake of this example
}

As you can see, there's an attempt to populate a std::map< std::string, int > using the xlw class MyArray: in the Excel spreadsheet people could be a range of strings, hence C++ code should see something like a std::vector< std::string > and thus it should use it to populate myMap with proper std::pair< std::string, int >.

However, this doesn't build.

Main issue is that MyArray is a typedef defined in mycontainers.h:

// ===== mycontainers.h =====
// Line 68
// ...
   typedef std::vector<double> MyArray;

Therefore, no way it can be translated into a container able to manage strings: just doubles. Even though in his book's chapter related to xlw Joshi says...

[...] The class MyArray is also defined via a typedef in MyContainers.h. The default is to typedef to std::vector. It must have .size(), a constructor taking the size, and operator[] defined.

...it is not sufficient to add

typedef std::vector< std::string > MyStrArray;

neither to mycontainers.h nor to any header file of my project.

Questions

  1. How may I populate that std::map< std::string, int> by reading a range of strings from Excel?
  2. How may I define new containers via typedef according to my desired types/classes in order to manage all possible inputs from Excel?
Lisa Ann
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  • Is mycontainers.h part of the sample template? It looks like it is not part of the xlw documentation. I would think you could just change the typedef. – NathanOliver Feb 03 '15 at 16:54
  • It's an external dependency. I've tried to amend the code by adding that definition but it doesn't build anyway. I guess something else must be done elsewhere, but I can't figure out where or how. – Lisa Ann Feb 03 '15 at 17:18
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    Have you tried with `typedef std::vector< std::wstring > MyStrArray;`? Excel strings shoud be unicode. – Enrico Detoma Feb 04 '15 at 08:39

1 Answers1

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The MyArray class is only intended to represent arrays of doubles. The typedef is so you can use your favourite such class.

The CellMatrix class allows you to input data of any type. You simply test each element of the CellMatrix for its type and then do what you want with it.

Mark Joshi
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