Which, if any, of the following assignments are invalid? If they are valid, explain what they do.
int i = 0, &r1 = i; double d = 0, &r2 = d;
- (a) r2 = 3.14159;
- (b) r2 = r1;
- (c) i = r2;
- (d) r1 = d;
(a)是可行的,使得d的值改变为3.14159
(b)是可行的,使得d的值改变为0
(c)是可行的,i的值为0
(d)是可行的,i的值变化为0