How write a file using StreamWriter in Windows 8?

Instead of StreamWriter you would use something like this:

StorageFolder folder = ApplicationData.Current.LocalFolder;
StorageFile file = await folder.CreateFileAsync();

using (IRandomAccessStream fileStream = await file.OpenAsync(FileAccessMode.ReadWrite))
    using (IOutputStream outputStream = fileStream.GetOutputStreamAt(0))
        using (DataWriter dataWriter = new DataWriter(outputStream))
            //TODO: Replace "Bytes" with the type you want to write.
            await dataWriter.StoreAsync();

        await outputStream.FlushAsync();

You can look at the StringIOExtensions class in the WinRTXamlToolkit library for sample use.


While all the above should work – they were written before the FileIO class became available in WinRT, which simplifies most of the common scenarios that the above solution solves since you can now just call await FileIO.WriteTextAsync(file, contents) to write text into file and there are also similar methods to read, write or append strings, bytes, lists of strings or IBuffers.

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