17-4.txt

编译原理课程设计大作业PL0文法简易编译器

const a=0, b=1;
var x,y:integer;
procedure test1;
  const a=3,b=4;
  var x,y:integer;
  procedure test2;
    const a=5,b=6;
    begin
      write("a= ",a);
      write("b= ",b);
      write("x= ",x);
      write("y= ",y)
    end;
  begin
    read(x,y);
    write("a= ",a);
    write("b= ",b);
    write("x= ",x);
    write("y= ",y);
    test2 
  end;
procedure test3;
  const a=7,b=8;
  var x,y:integer;
  procedure test4;
    const a=9,b=10;
    begin
      write("a= ",a);
      write("b= ",b);
      write("x= ",x);
      write("y= ",y)
    end;
  begin
    read(x,y);
    write("a= ",a);
    write("b= ",b);
    write("x= ",x);
    write("y= ",y);
    test1 
  end;
begin
  read(x,y);
  write("a= ",a);
  write("b= ",b);
  write("x= ",x);
  write("y= ",y);
  test3
end.