按键判断的几种方法

1.利switch.....case 语句，由于switch语句可以判断离散值，所以可以用来判断按键

        eg：switch(P1)

               {

                 case 0xfe:delay();

                               if(P1=0xfe)

                                   {}

                                break;

               case 0xfd:delay();

                               if(P1=0xfd)

                                   {}

                                break;

              default:        break;

            }

  通过对P1值的判断可以确定是哪个独立按键按下了。

 

2.switch(P1)

             {

               case  0xfe:delay();                     //去抖

                               if(P1=0xfe)                  //按键按下

                                    {

                                     for(;;)

                                        {

                                          if(P1=0xfe)               //确认按下

                                             continue;

                                              else  break;

                                          }

                                     for(;;)

                                        {

                                           while(P1=0xfe);          //如为干扰，继续循环

                                           if(P1=0xfe)

                                             continue;

                                              else  break;        //按键释放

                                          }

                                        disp5();              //执行按键的功能

                                }

 

 

              }