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#include<reg51.h><br />sbit d1=P1^0;<br />sbit d2=P1^1;<br />sbit d3=P1^2;<br />sbit d4=P1^3;<br />sbit a1=P3^2;<br />sbit key1=P3^0;<br />sbit key2=P3^1;<br />sbit key3=P3^2;<br />sbit key4=P3^3;<br />unsigned int a;<br /><br />void main()<br />{             <br />                    <br />        P3=0xff;<br />                if(a1==0)<br />                    key1=1;<br />                    key2=1;<br />        while(1)<br />        {<br />                <br /><br />                if(key1==0)<br />                    a=51000;<br />                     d1=0;<br />                    while(a--);<br />                    d1=1;<br />                                   a=51000;<br />                                   while(a--);<br />                    <br />                <br />                if(key2==0)<br />                    a=51000;<br />                    d2=0;    <br />                    while(a--);<br />                    d2=1;<br />                    a=51000;<br />                    while(a--);<br />                                <br />                <br />                if(key1==0&key4==0)<br />                    d1=0;<br />                    d4=0;<br />                    key2=1;<br />                    <br /><br />                if(key2==0&key4==0)<br />                    d2=0;<br />                    d4=0;<br />                    key1=1;<br />                    <br /><br />                if(key4==0)<br />                    key3=0;<br />                    d3=0;<br />                    key3=1;<br />                    d3=1;<br />                <br />                <br />        }<br />}<br /><br />这个是我看到的一个程序  <br />我觉得if语句是不是太多了,而且不能加else 如果加了立刻会出现错误,不加就什么错误也没有,咱是新手搞不明白为什么,请教高手看看吧~<br />这个程序是想表达一个选择的结果,如果不用if语句能用别的吗?<br /> |   
     
  
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