我用 c++/cx 为 Metro 应用程序编写的文件有什么问题？

Question

我正在使用以下代码尝试写入文件：

StorageFolder ^localFolder = ApplicationData::Current->LocalFolder;
concurrency::task<StorageFile^> fileOperation = localFolder->CreateFileAsync("data.txt", CreationCollisionOption::ReplaceExisting);
fileOperation.then([this](StorageFile^ sampleFile)
{
    ::Globalization::DateTimeFormatting::DateTimeFormatter("longtime");
    Platform::String ^str; // other str stuff here

    return FileIO::WriteTextAsync(sampleFile, str);
}).then([this](concurrency::task<void> previousOperation) {
    try {
        previousOperation.get();
    } catch (Platform::Exception^) {
    }
});

感谢“Sometimes A Developer”修复了错误

我从这里得到代码： http://msdn.microsoft.com/en-us/library/windows/apps/xaml/hh700361.aspx

Answer 1

只需替换这一行：

concurrency::task<StorageFile^> fileOperation = localFolder->CreateFileAsync("data.txt",
    CreationCollisionOption::ReplaceExisting);

用这一行：

concurrency::task<StorageFile^> fileOperation(localFolder->CreateFileAsync("data.txt",
    CreationCollisionOption::ReplaceExisting));