Windows Store App comment supprimer le texte du fichier

Question

Dans une application Windows Store, comment puis-je supprimer du texte d'un fichier? Par exemple

Si je

StorageFile file = await roamingfolder.CreateFileAsync(filename, 
    CreationCollisionOption.OpenIfExists); 
await FileIO.AppendTextAsync(file, temp); 

Comment puis-je supprimer un texte de ce fichier?

Answer 1

Vous lisez généralement le texte dans une chaîne, supprimez le texte et réécrivez le fichier.

Answer 2

Ici, je reçois un fichier, puis je mets le contenu à un stringbuilder puis terminez les opérations de chaîne, enfin mettre la chaîne dans le fichier en utilisant DataWriter

public static async Task UpdateTextContent(string contentItemId) 
     { 
      var storageFolder = await ApplicationData.Current.LocalFolder.GetFolderAsync(TARGET_FOLDER); 
      StorageFile sf = null; 
      try 
      { 
       //get content of the file make sure that it exist 
       sf = await storageFolder.GetFileAsync(TARGET_FILE); 
      } 
      catch (Exception ex) 
      { 

      } 

      if (sf != null) 
      { 
       var targettxtfile = await Windows.Storage.FileIO.ReadTextAsync(sf); 


       var sbProcessedTextToWrite = new StringBuilder(targettxtfile); 



       if (targettxtfile.IndexOf(contentItemId) >= 0) 
       { 
        string startmarker = new StringBuilder("[").Append(contentItemId).Append("#start]").ToString(); 
        string endmarker = new StringBuilder("[").Append(contentItemId).Append("#end]").ToString(); 

        int start = sbProcessedTextToWrite.ToString().IndexOf(startmarker); 
        int end = sbProcessedTextToWrite.ToString().IndexOf(endmarker); 

        int slen = end + endmarker.Length - start; 

        //compute position to remove 
        sbProcessedTextToWrite.Remove(start, slen); 
       } 

       using (IRandomAccessStream fileStream = await sf.OpenAsync(FileAccessMode.ReadWrite)) 
       { 
        using (IOutputStream outputStream = fileStream.GetOutputStreamAt(0)) 
        { 
         using (DataWriter dataWriter = new DataWriter(outputStream)) 
         { 

          dataWriter.WriteString(sbProcessedTextToWrite.ToString());        

          await dataWriter.StoreAsync(); 

          // For the in-memory stream implementation we are using, the flushAsync call 
          // is superfluous,but other types of streams may require it. 
          await dataWriter.FlushAsync(); 

          // In order to prolong the lifetime of the stream, detach it from the 
          // DataWriter so that it will not be closed when Dispose() is called on 
          // dataWriter. Were we to fail to detach the stream, the call to 
          // dataWriter.Dispose() would close the underlying stream, preventing 
          // its subsequent use by the DataReader below. 
          dataWriter.DetachStream(); 
         } 

         //same here flush the outputStream as well 
         await outputStream.FlushAsync(); 
        } 
       } 
      } 


     } 

Some references for this code