用Turbo Pascal 7.0编一个程序

program oper;
var x,y,n:real;
operator:char;
begin
write('input x,y:');readln(x,y);
write('input opearator:');readln(operator);
case operator of
'+':n:=x+y;
'-':n:=x-y;
'*':n:=x*y;
'/':if y=0 then
begin writeln('divide is zero!');halt;end
else n:=x/y;
else begin writeln('input operator error!');halt;end
end;
writeln(x:6:2,operator,y:6:2,'=',n:6:2);
end.

那些运算符？

得 先规定有哪些算符才能进行判断怎末算

var a,b,n:integer;c:char;
begin
readln(a,c,b);
case c of
'+':n:=a+b;
'-':n:=a-b;
'*':n:=a*b;
'/':n:=a/b;
end;
writeln(n);
end.