📄 6.6.5.htm

📁 建立《编译原理网络课程》的目的不仅使学生掌握构造编译程序的原理和技术
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<font class="title2"><b>练习</b></font>
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<a name="6.1"></a>

6.1 利用Pascal的作用域规则，试确定下面Pascal程序中名字a和b的每一次出现所应用的说明。                                      
        <br>
        &nbsp;&nbsp;&nbsp; <b><font color="#0000FF">program</font></b> a（input，output）； <br>                                      
        &nbsp;&nbsp;&nbsp; <b><font color="#0000FF">procedure</font></b> b（u,v，x，y： 
<b><font color="#0000FF"> integer</font></b>）； <br>                                     
        &nbsp;&nbsp;&nbsp; <b>&nbsp;&nbsp;&nbsp;<font color="#0000FF">var</font></b> a:record a，b: 
<font color="#0000FF"><b> integer</b></font>                                       
        <b><font color="#0000FF">end</font></b>； <br>
        &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;b: record b，a: <font color="#0000FF"><b>                                      
        integer</b></font> <b><font color="#0000FF">end</font></b>； <br>                                     
        &nbsp;&nbsp;&nbsp; <b>&nbsp;&nbsp;&nbsp;<font color="#0000FF">begin</font></b> <br>                                     
        &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<font color="#0000FF"><b>with</b></font> a 
<font color="#0000FF"><b> do begin</b></font>                                       
        a：＝u；b：＝v <b><font color="#0000FF">end</font></b>； <br>                                     
        &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<font color="#0000FF"><b>with</b></font> b 
<font color="#0000FF"><b> do begin</b></font>                                       
        a：＝x; b：＝y <b><font color="#0000FF">end</font></b>； <br>                                     
        &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;writeln（a. a，a.                                       
        b，b．a，b.b） <br>
        &nbsp;&nbsp;&nbsp; <b>&nbsp;&nbsp;&nbsp;<font color="#0000FF">end</font></b>; <br>                                     
        &nbsp;&nbsp;&nbsp; <b><font color="#0000FF">begin</font></b> <br>                                     
        &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;b（1，2，3．4) <br>                                      
        &nbsp;&nbsp;&nbsp; <b><font color="#0000FF">end</font></b>.                                    
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<a name="6.2"></a>
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6.2 试问下面的程序将有怎样的输出？分别假定： <br>                                     
        &nbsp;&nbsp;&nbsp;（a）传值调用（call-by-value）； <br>
        &nbsp;&nbsp;&nbsp;（b) 引用调用（call-by-reference）； <br>                                      
        &nbsp;&nbsp;&nbsp; (c）复制恢复（copy-restore）； <br>                                      
        &nbsp;&nbsp;&nbsp;（d）传名调用（call-by-name）。 <br>
        &nbsp;&nbsp;&nbsp; <b><font color="#0000FF">program</font></b> main(input,output）； <br>                                      
        &nbsp;&nbsp;&nbsp; <b>&nbsp;&nbsp;&nbsp;<font color="#0000FF">procedure</font></b> p（x,y,z）； <br>                                      
        &nbsp;&nbsp;&nbsp; <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<font color="#0000FF">begin</font></b> <br>                                     
        &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;y：＝y＋1；                                       
        <br>
        &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;z：＝z＋x；                                       
        <br>
        &nbsp;&nbsp;&nbsp; <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<font color="#0000FF">end</font></b>； <br>                                     
        &nbsp;&nbsp;&nbsp; <b>&nbsp;&nbsp;&nbsp;<font color="#0000FF">begin</font></b> <br>                                     
        &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;a：＝2； <br>                                      
        &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;b：＝3； <br>                                      
        &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;p(a＋b,a,a)；                                       
        <br>
        &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;print a <br>                                      
        &nbsp;&nbsp;&nbsp; <b>&nbsp;&nbsp;&nbsp;<font color="#0000FF">end</font></b>.                               
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