计算输入的日期距今有多少天

写的简单程序，主要用于的计算出输入的日期距今有多少天

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----
     目录           0  2015-07-13 11:23  WindowsFormsApplication5\
     目录           0  2015-07-13 11:23  WindowsFormsApplication5\WindowsFormsApplication5\
     文件         914  2015-07-13 11:23  WindowsFormsApplication5\WindowsFormsApplication5.sln
     文件       19968  2015-08-19 15:54  WindowsFormsApplication5\WindowsFormsApplication5.suo
     目录           0  2015-07-13 11:23  WindowsFormsApplication5\WindowsFormsApplication5\bin\
     目录           0  2015-07-13 11:29  WindowsFormsApplication5\WindowsFormsApplication5\bin\Debug\
     文件        9728  2015-08-08 15:07  WindowsFormsApplication5\WindowsFormsApplication5\bin\Debug\WindowsFormsApplication5.exe
     文件       26112  2015-08-08 15:07  WindowsFormsApplication5\WindowsFormsApplication5\bin\Debug\WindowsFormsApplication5.pdb
     文件       11600  2015-08-21 17:07  WindowsFormsApplication5\WindowsFormsApplication5\bin\Debug\WindowsFormsApplication5.vshost.exe
     文件         490  2010-03-17 22:39  WindowsFormsApplication5\WindowsFormsApplication5\bin\Debug\WindowsFormsApplication5.vshost.exe.manifest
     文件         870  2015-07-13 11:29  WindowsFormsApplication5\WindowsFormsApplication5\Form1.cs
     文件        3494  2015-07-13 11:26  WindowsFormsApplication5\WindowsFormsApplication5\Form1.Designer.cs
     文件        5817  2015-07-13 11:26  WindowsFormsApplication5\WindowsFormsApplication5\Form1.resx
     目录           0  2015-07-13 11:23  WindowsFormsApplication5\WindowsFormsApplication5\obj\
     目录           0  2015-07-13 11:23  WindowsFormsApplication5\WindowsFormsApplication5\obj\x86\
     目录           0  2015-08-08 15:07  WindowsFormsApplication5\WindowsFormsApplication5\obj\x86\Debug\
     文件        4501  2015-08-08 15:07  WindowsFormsApplication5\WindowsFormsApplication5\obj\x86\Debug\DesignTimeResolveAssemblyReferences.cache
     文件        6481  2015-08-08 15:07  WindowsFormsApplication5\WindowsFormsApplication5\obj\x86\Debug\DesignTimeResolveAssemblyReferencesInput.cache
     文件         488  2015-07-13 11:29  WindowsFormsApplication5\WindowsFormsApplication5\obj\x86\Debug\GenerateResource.read.1.tlog
     文件        1142  2015-07-13 11:29  WindowsFormsApplication5\WindowsFormsApplication5\obj\x86\Debug\GenerateResource.write.1.tlog
     文件        8031  2015-08-08 15:07  WindowsFormsApplication5\WindowsFormsApplication5\obj\x86\Debug\ResolveAssemblyReference.cache
     目录           0  2015-07-13 11:23  WindowsFormsApplication5\WindowsFormsApplication5\obj\x86\Debug\TempPE\
     文件        1339  2015-08-21 17:07  WindowsFormsApplication5\WindowsFormsApplication5\obj\x86\Debug\WindowsFormsApplication5.csproj.FileListAbsolute.txt
     文件        9728  2015-08-08 15:07  WindowsFormsApplication5\WindowsFormsApplication5\obj\x86\Debug\WindowsFormsApplication5.exe
     文件         180  2015-07-13 11:29  WindowsFormsApplication5\WindowsFormsApplication5\obj\x86\Debug\WindowsFormsApplication5.Form1.resources
     文件       26112  2015-08-08 15:07  WindowsFormsApplication5\WindowsFormsApplication5\obj\x86\Debug\WindowsFormsApplication5.pdb
     文件         180  2015-07-13 11:29  WindowsFormsApplication5\WindowsFormsApplication5\obj\x86\Debug\WindowsFormsApplication5.Properties.Resources.resources
     文件         505  2015-07-13 11:23  WindowsFormsApplication5\WindowsFormsApplication5\Program.cs
     目录           0  2015-07-13 11:23  WindowsFormsApplication5\WindowsFormsApplication5\Properties\
     文件        1398  2015-07-13 11:23  WindowsFormsApplication5\WindowsFormsApplication5\Properties\AssemblyInfo.cs
     文件        2899  2015-07-13 11:23  WindowsFormsApplication5\WindowsFormsApplication5\Properties\Resources.Designer.cs
............此处省略4个文件信息