更改二级指针所指内容？？
int *pi = NULL;
int **ppi = NULL;
pi = (int*)malloc(4);
memset(pi,0,4);
ppi = (int**)malloc(4);
memset(ppi,(int)pi,4); //所指内容置为pi值
**ppi = 10; //!!!挂掉
////////////////////////////
怎么修改可以赋给**ppi值
[解决办法]
void *memset( void *dest, int c, size_t count );
Return Value
memset returns the value of dest.
Parameters
dest
Pointer to destination
c
Character to set
count
Number of characters
Remarks
The memset function sets the first count bytes of dest to the character c.
故在此函数仅仅取了pi中的一个字节大小的内容，然后重复了4次，故指向不对了
