两个大数相乘

#include "stdafx.h"
#include <iostream>



void multiply(char* a,char* b,char* c)
{
	int i,j,ca,cb,* s;
	ca=strlen(a);
	cb=strlen(b);
	s=(int*)malloc(sizeof(int)*(ca+cb));
	for (i=0;i<ca+cb;i++)
		s[i]=0;
	for (i=0;i<ca;i++)				//s[0]作为最高位，进位
		for (j=0;j<cb;j++)
			s[i+j+1]+=(a[i]-'0')*(b[j]-'0');
	for (i=ca+cb-1;i>=0;i--)		//处理进位
		{
		if (s[i]>=10)                   
			s[i-1]+=s[i]/10; 
			s[i]%=10;
		}
		i=0;
		while (s[i]==0)              //找出第一个非零位
			i++;
		for (j=0;i<ca+cb;i++,j++)
			c[j]=s[i]+'0';
		if(0 == j)					//处理和0相乘时的情况
		{
			c[0] = '0';
			j++;
		}
		c[j]='\0';
		free(s);
}

int main()

{
	char *a="463434436547465646347676434343";
	char *b="1464534165468468454";
	char *c=new char[256];
	multiply(a,b,c);
	std::cout<<c<<std::endl;
}