相关疑难解决方法(0)

请使用以下代码:

int *p = malloc(2 * sizeof *p);

p[0] = 10;  //Using the two spaces I
p[1] = 20;  //allocated with malloc before.

p[2] = 30;  //Using another space that I didn't allocate for. 

printf("%d", *(p+1)); //Correctly prints 20
printf("%d", *(p+2)); //Also, correctly prints 30
                      //although I didn't allocate space for it

malloc(2 * sizeof *p)我用这条线为两个整数分配空间,对吧？但是如果我添加int到第三个位置,我仍然可以正确分配并可检索.

所以我的问题是,为什么在使用时指定尺寸malloc？