函数名: unlock 
 功  能: 解除文件共享锁 
 用  法: #include <io.h> 
         int unlock(int handle, long offset, long length); 
 程序例: 
#include <io.h> 
 #include <fcntl.h> 
 #include <sys\stat.h> 
 #include <process.h> 
 #include <share.h> 
 #include <stdio.h> 
int main(void) 
 { 
    int handle, status; 
    long length; 
handle = sopen("c:\\autoexec.bat",O_RDONLY,SH_DENYNO,S_IREAD);
   if (handle < 0) 
    { 
        printf("sopen failed\n"); 
        exit(1); 
    } 
   length = filelength(handle); 
    status = lock(handle,0L,length/2); 
   if (status == 0) 
       printf("lock succeeded\n"); 
    else 
       printf("lock failed\n"); 
status = unlock(handle,0L,length/2);
   if (status == 0) 
       printf("unlock succeeded\n"); 
    else 
       printf("unlock failed\n"); 
   close(handle); 
    return 0; 
 }