大数相乘

要机试了，练了几道题。贴一下大数相乘的写法，关键是加法：

#include<iostream>
#include<string>
using namespace std;
#define Max 100
void	Add(char*cA,int nNum)
{
	nNum=nNum+*cA-'0';
	int	high=nNum/10;
	int low=nNum%10;
	*cA=low+'0';
	if(high==0)
		return;
	else
	{
		Add(cA+1,high);
	}
		
}
void main()
{
	char cA1[Max],cA2[Max],cA3[Max+Max];
	int	cA1length=0,cA2length=0;
	string	str;
	for(int i=0; i<Max;++i)
	{
		cA1[i]='0';
		cA2[i]='0';
	}
	for(int i=0;i<Max*2;++i)
	{
		cA3[i]='0';
	}
	cout<<"输入两个大数："<<endl;
	cin>>str;
	for(int i=0;i<str.length();++i)
	{
		cA1length++;
		cA1[i]=str[str.length()-1-i];
	}
	str.clear();
	cin>>str;
	for(int i=0;i<str.length();++i)
	{	cA2length++;
		cA2[i]=str[str.length()-1-i];
	}
	for(int i=0;i<cA2length;++i)
	{
		for(int j=0;j<cA1length;++j)
		{
			int Temp=(cA2[i]-'0')*(cA1[j]-'0');
			Add(cA3+i+j,Temp);
		}
	}
	int nUp=cA1length+cA2length;
	while(cA3[nUp]=='0')
		nUp--;
	while(nUp!=-1)
	{
		cout<<cA3[nUp];
		nUp--;
	}
}