Using native Windows natural order sorting in a custom program

Question

As a programmer, you have probably had to use or create some kind of string comparison function. Usually, these are pretty simple:

function compare(s1, s1) { return s1.toLowerCase() - s2.toLowerCase(); }

This works great for the vast majority of cases. However, Windows (XP and later) sorts files differently -- and better! -- than a poor ASCII implementation.

How can I create a Minimal, Complete, and Verifiable example of native Windows natural order sorting in a custom program?

Everything I have read points to using the StrCmpLogicalW function in shlwapi.dll. That's great! But how can this function be used inside a custom C/C++ program?

I am not interested in re-implementing the compare function. I have already seen this, this, this, this, and this. These are no doubt very close approximations, but I just want to link or call the Windows API function in my program.

Here are some other things I have researched and tried already:

• reading the documentation on shlwapi.dll and StrCmpLogicalW from Microsoft
• finding a (supposedly) complete program posted from an earlier Q&A here on StackOverflow
• compiling several small code samples for Visual Studio 2010 Express, both C++ and C# versions (fatal error C1190: managed targeted code requires a '/clr' option... really?)
• compiling several small code samples for Visual Studio 2012 Express, because some article said this would get rid of the earlier compile error about the /clr option, but just got a bunch of different compile errors instead
• tried compiling several small code samples for Eclipse C++ with MinGW

When I first started looking into this, I thought, "It's just the Windows API, this will be easy!" I have yet to come up with a working program in any language.

I have been doing C/C++ and Unix/DOS/Windows shell scripting for a long time, and using an API has never been so irksome. Shame on you, Microsoft.

---

Also, I've already read the rants about ASCII sorting, but thank you. These contained some fertile soil for some good thinking.

https://blog.codinghorror.com/sorting-for-humans-natural-sort-order/

http://weblog.masukomi.org/2007/12/10/alphabetical-asciibetical/

Answer 1

C++:

#include <windows.h>
#include <shlwapi.h>
#pragma comment(lib, "shlwapi.lib")

#include <algorithm>
#include <vector>
#include <string>
#include <iostream>

bool str_cmp_logical(std::wstring const &lhs, std::wstring const &rhs)
{
    return StrCmpLogicalW(lhs.c_str(), rhs.c_str()) < 1;
}

int main()
{
    std::vector<std::wstring> foo{
        L"20string", L"2string", L"3string", L"st20ring", L"st2ring",
        L"st3ring", L"string2", L"string20", L"string3"
    };

    for (auto const &f : foo)
        std::wcout << f << L' ';
    std::wcout.put(L'\n');

    std::sort(foo.begin(), foo.end(), str_cmp_logical);

    for (auto const &f : foo)
        std::wcout << f << L' ';
    std::wcout.put(L'\n');
}

Output:

20string 2string 3string st20ring st2ring st3ring string2 string20 string3
2string 3string 20string st2ring st3ring st20ring string2 string3 string20

---

Trying to compile the code with MinGW failed, because the version of <shlwapi.h> that comes with its package w32api doesn't provide a prototype for StrCmpLogicalW(). When I declared it myself i got

C:\MinGW\bin>"g++.exe" -lshlwapi C:\Users\sword\source\repos\Codefun\main.cpp
C:\Users\sword\AppData\Local\Temp\ccMrmLbD.o:main.cpp:(.text+0x23): undefined reference to `StrCmpLogicalW(wchar_t const*, wchar_t const*)'
collect2.exe: error: ld returned 1 exit status

So the libraries shipped with MinGW don't seem to be aware of StrCmpLogicalW().

It should work with Mingw-w64, though.

Answer 2

Turns out, DLLs can be called easily with AutoIt or AutoHotKey.

I have distilled this post from the AutoIt forums into a minimal working example:

Func _StrCmpLogicalW($s1, $s2)
   Return DllCall('shlwapi.dll', 'int', 'StrCmpLogicalW', 'wstr', $s1, 'wstr', $s2)[0]
EndFunc

And here is a minimal example distilled from this archive post on the AutoHotkey forums:

_StrCmpLogicalW(s1, s2)
{
   VarSetCapacity(ws1, StrLen(s1)*2+1,0), DllCall("MultiByteToWideChar", "UInt",0, "UInt",0, "UInt",&s1, "Int",-1, "UInt",&ws1, "Int",StrLen(s1)+1)
   VarSetCapacity(ws2, StrLen(s2)*2+1,0), DllCall("MultiByteToWideChar", "UInt",0, "UInt",0, "UInt",&s2, "Int",-1, "UInt",&ws2, "Int",StrLen(s2)+1)
   return DllCall("Shlwapi.dll\StrCmpLogicalW","UInt",&ws1,"UInt",&ws2)
}

That's it! The function takes two stings and returns -1/0/+1 like ever other comparison function in the world.

Combine this with a sorting algorithm (such as _ArrayMultiColSort(), _ArrayCustomSort() for AutoIt) and now you can Quicksort entire lists.

(Please, do not use Bubble Sort. Think of the children.)