链表实现的大整数乘法

#include<iostream>
#include<malloc.h>

using namespace std;

// linked list struct
typedef struct Node {
	char buffer;        // enter a char
	int integer;        // store integer
	int number = 0;     // record number
	struct Node* next;  // pointer to next
	Node(int elem) :integer(elem), next(NULL) {}
}*List;

// initialize the linked list
void init_list(List& L) {
	// reverse insert
	List p = new Node(0);
	L = new Node(0);
	// exclude starting with zero
	while (cin >> p->buffer) {
		if (p->buffer != '0') {
			break;
		}
	}
	while (p->buffer >= '0' && p->buffer <= '9') {
		p->integer = p->buffer - '0';
		p->next = L->next;
		L->next = p;
		L->number++;
		p = new Node(0);
		cin >> p->buffer;
	}
}

// insert a single node
void insert_node(List& L, int elem) {
	List p = new Node(0);
	p->integer = elem;
	p->next = L->next;
	L->next = p;
}

// reverse linked list
void reverse_l