C++WinRT does not correctly handles Chinese characters using Windows.Foundation.Uri

peter li 6

I have a uri with Chinese character and query string that needs to be parsed with Windows.Foundation.Uri. Using C++WinRT, it always returns me an empty result. But equivalent C# code does returns me expected result.

I have tried changing the file encoding to either UTF-8 and UTF-8 BOM, nothing worked.

With C++WinRT, create a C++WinRT console application:

    winrt::Windows::Foundation::Uri uri{ LR"(myapp://open?file="C:/我.txt")" };
    winrt::Windows::Foundation::WwwFormUrlDecoder parsed{ uri.Query() };
    for (auto entry : parsed)
    {
        std::wcout << entry.Name().data() << L'\t' << entry.Value().data() << L'\n';
    }

With C#, create a UWP project:

            var uri = new Uri("myapp://open?file=\"C:/我.txt\"");
            var parsed = new WwwFormUrlDecoder(uri.Query);
            foreach (var entry in parsed)
            {
                Debug.WriteLine(entry);
            }

C# gives me expected result:

enter image description here

C++ gives me empty result:

enter image description here

Repro code here

Viorel 118.2K Reputation points

2024-07-08T19:36:51.6433333+00:00
It seems that the query must be escaped:

winrt::Windows::Foundation::Uri uri{ LR"(myapp://open?file=%22C:/%E6%88%91.txt%22)" };
peter li 6 Reputation points

2024-07-09T03:18:38.5333333+00:00

How do you get that escaped using WinRT apis? I tried AbsoluteCanonicalUri and it does not escape the double-quote. It returns myapp://open/?file="C:/%E6%88%91.txt"

Viorel 118.2K

I think that it is not necessary to escape the '"'. To build the Uri, try this:

winrt::hstring file = L"C:/我.txt";
winrt::Windows::Foundation::Uri uri{ L"myapp://open?file=" + winrt::Windows::Foundation::Uri::EscapeComponent( file ) };

winrt::Windows::Foundation::WwwFormUrlDecoder parsed{ uri.Query( ) };
// or: winrt::Windows::Foundation::WwwFormUrlDecoder parsed = uri.QueryParsed( );

for( auto entry : parsed )
{
    auto n = entry.Name( );
    auto v = entry.Value( );
    std::wcout << n.data() << L'\t' << v.data() << L'\n';
}

peter li 6 Reputation points

2024-07-09T03:58:24.7766667+00:00
Yeah I found that out. Also just in case other people found this, std::wcout might not correctly print the character. It does not print the chinese character in this case.

Add these lines before std::wcout

#include <io.h> #include <fcntl.h> _setmode(_fileno(stdout), _O_WTEXT); // or _O_U16TEXT, either work _setmode(_fileno(stdin), _O_WTEXT);
Junjie Zhu - MSFT 19,051 Reputation points Microsoft Vendor

2024-07-09T05:37:38.63+00:00

Hi @peter li ,

Welcome to Microsoft Q&A!

According to the Remarks

The Windows.Foundation.Uri class doesn't percent-encode non-ASCII characters in Uniform Resource Identifier (URI) where the scheme refers to a Windows file path (like ms-appx:). Windows.Foundation.Uri also interprets percent-encoding using the user's current codepage.

In C++/winrt it could be this potential factor that causes the unexpected behaviour.

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C++WinRT does not correctly handles Chinese characters using Windows.Foundation.Uri

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