读卡器dll的接口函数: 
  int   open_comm(int   comm_id); 
  int   CardReady(long   *snr); 
调用的方法是: 
  [DllImport( "...WM_Mifare.dll ",   CharSet   =   CharSet.Ansi)]\\dll是绝对路径 
public   static   extern   int   open_comm(string       comm_id); 

            public   int     InitReaderDll(string     comm_id) 
                {           
                                return   open_comm(comm_id);         
                } 


[DllImport( "E:\\.....WM_Mifare.dll ",   CharSet   =   CharSet.Ansi)]\\dll是绝对路径 
                public   static   extern   int   CardReady(string   snr); 

                public   int   DllReader(string   snr) 
                {     
                                return   CardReady(snr); 
                } 

调用指令: 
private   void   button2_Click(object   sender,   EventArgs   e) 
                { 
                        this.skclass.InitReaderDll(a); 
                              this.skclass.DllReader(i); 
                        this.textBox3.Text   =   i; 
                } 


int   open_comm(int   comm_id); 
  int   CardReady(long   *snr); 

对应： 
public   static   extern   int   open_comm(int   comm_id); 
public   static   extern   int   CardReady(ref   long   snr);

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activeX

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activeX