[C#]讀取Word, Excel, PowerPoint, PDF檔案資料

記錄找到的resource，如何用C#讀取這些常見檔案格式(三個願望，一次滿足)。

• 讀取PDF
• 1. [C#] 讀取 PDF 檔 
  2. How to read pdf files using C# .NET
  3. Extract Text from PDF in C# (100% .NET) , License: The Code Project Open License (CPOL)
  4. Converting PDF to Text in C#,  License: The Code Project Open License (CPOL)
• 讀取Excel
  1. [C#] - 讀取Excel檔案
• 讀取Word
  1. Quick Tutorial: How To Read Microsoft Word File in C#
  2. Reading a word document using C#
• 讀取PowerPoint
  1. C#: How to read from Microsoft PowerPoint file ppt