Question

如果连接了多个USB设备（至少一个包含密钥），则代码返回false。

如果其中一个连接的usb设备有密钥，我想让这段代码返回true，

List<DriveInfo> list = new List<DriveInfo>(DriveInfo.GetDrives());

foreach (DriveInfo drive in list)
{
   if (drive.DriveType == DriveType.Removable)
   {
       if ((File.Exists(drive.RootDirectory + "Key.txt")) && 
           File.Exists(drive.RootDirectory + "SerialNumber.txt"))
       {
           string KeyFromUsb = (System.IO.File.ReadAllText(drive.RootDirectory + "Key.txt"));
           string serialusb = (System.IO.File.ReadAllText(drive.RootDirectory + "SerialNumber.txt"));
           int serialNumbeFromUsb = Convert.ToInt32(serialusb);
           string KeyFromDataBase = FoundKey(serialNumbeFromUsb);

           if (KeyFromDataBase == KeyFromUsb)
           {
              ok = true;
           }
           else
           {
               return false;
           }
        }
    }
}

Answer 1

很常见的逻辑问题。

将ok = true更改为return true并将return false移至循环外部。

List<DriveInfo> list = new List<DriveInfo>(DriveInfo.GetDrives());

foreach (DriveInfo drive in list)
{
   if (drive.DriveType == DriveType.Removable)
   {
       if ((File.Exists(drive.RootDirectory + "Key.txt")) && 
           File.Exists(drive.RootDirectory + "SerialNumber.txt"))
       {
           string KeyFromUsb = (System.IO.File.ReadAllText(drive.RootDirectory + "Key.txt"));
           string serialusb = (System.IO.File.ReadAllText(drive.RootDirectory + "SerialNumber.txt"));
           int serialNumbeFromUsb = Convert.ToInt32(serialusb);
           string KeyFromDataBase = FoundKey(serialNumbeFromUsb);

           if (KeyFromDataBase == KeyFromUsb)
           {
              return true;
           }
        }
    }
}
return false;

Answer 2

List<DriveInfo> list = new List<DriveInfo>(DriveInfo.GetDrives());
//var i = 0;
int i = 0;
foreach (DriveInfo drive in list)
{
   if (drive.DriveType == DriveType.Removable)
   {
       if ((File.Exists(drive.RootDirectory + "Key.txt")) && 
           File.Exists(drive.RootDirectory + "SerialNumber.txt"))
       {
           string KeyFromUsb = (System.IO.File.ReadAllText(drive.RootDirectory + "Key.txt"));
           string serialusb = (System.IO.File.ReadAllText(drive.RootDirectory + "SerialNumber.txt"));
           int serialNumbeFromUsb = Convert.ToInt32(serialusb);
           string KeyFromDataBase = FoundKey(serialNumbeFromUsb);

           if (KeyFromDataBase == KeyFromUsb)
           {
              i = 1; //or simply return true, this will exit the loop
           }
        }
    }
}

if(i == 1)
{
    ok = true;
}

或简单地返回true。（不要在foreach循环中返回false）。

Answer 3

      List<DriveInfo> list = new List<DriveInfo>(DriveInfo.GetDrives());
      var condSatisfied = false;

      foreach (DriveInfo drive in list)
      {
          if (drive.DriveType == DriveType.Removable)
          {
              if ((File.Exists(drive.RootDirectory + "Key.txt")) && 
                 File.Exists(drive.RootDirectory + "SerialNumber.txt"))
               {
                   string KeyFromUsb = (System.IO.File.ReadAllText(drive.RootDirectory + "Key.txt"));
                   string serialusb = (System.IO.File.ReadAllText(drive.RootDirectory + "SerialNumber.txt"));
                 int serialNumbeFromUsb = Convert.ToInt32(serialusb);
                   string KeyFromDataBase = FoundKey(serialNumbeFromUsb);

                   if (KeyFromDataBase == KeyFromUsb)
                  {
                      ok = true;
                     condSatisfied = true;
                   }
               }
           }
        }

       return condSatisfied

.net应用程序中的c＃代码问题

3 个答案: