字节集,a和b的值是多少

好的,我将解释您可能通过调试或简单地阅读有关Pascal的教科书来发现什么:

线路:

c := (a+b)*(a-b);

是否执行以下操作:

a + b is the union of the two sets, i.e. all elements that are 
      in a or in b or in both, so here, that is [2, 3];
a - b is the difference of the two sets, i.e. it is a minus the
      elements of a that happen to be in b too. In this case, no 
      common elements to be removed, so the result is the same as a, 
      i.e. [3]
x * y is the intersection of the two sets, i.e. elements that are in 
      x as well as in y (i.e. a set with the elements both have in common).

说 x := a + b; y := a - b; ,则可将其切除为:

x := a + b; // [3] + [2] --> [2, 3]
y := a - b; // [3] - [2] --> [3]
c := x * y; // [2, 3] * [3] --> [3]