1.txt

大数乘法函数Multiply： 输入：两个任意长度的10进制整数序列字符串

#include<iostream.h>
#include<string.h>
#define MAX_DIGITS 100
void Multiply(char*mulor,char*mulant,char*result);
void main()
{
	char mulor[MAX_DIGITS+1];
	char mulant[MAX_DIGITS+1];
	char result[2*MAX_DIGITS+1];
    
	cout<<"input one number ";
	cin>>mulor;
	cout<<"input another number ";
	cin>>mulant;
	
	char *ptor = mulor;
	char *ptant = mulant;
	
	Multiply(mulor,mulant,result);
	cout<<mulor<<" * "<<mulant<<" = "<<result<<endl;

}

void Multiply(char*mulor,char*mulant,char*result)
{
	char one[MAX_DIGITS];
	char two[MAX_DIGITS];
	char rel[2*MAX_DIGITS];
	int pro[2*MAX_DIGITS];
	
	int row = strlen(mulant);//?ˊ?t col = strlen(mulor);//???ˊ?	int i,j;
	strcpy(one,mulor);
	strcpy(two,mulant);
	
	for (i=0;i<2*MAX_DIGITS;i++)
		pro[i]=0;
	for(i = row-1; i >=0; i--)
		for(j = col-1 ; j >= 0; j--)
		{
			int product = (one[j]-'0')*(two[i]-'0');
			pro[i+j+0] += product/10 ;
			pro[i+j+1] += product%10 ;
		}
		for(i = row+col-1; i>0;i--)
		{
			if(pro[i]>=10)
			{
				pro[i-1] +=pro[i]/10;
				pro[i] =pro[i]%10;      
			}
		}
		int pos =0;
		for(i = 0;i<row +col;i++)
			if (pro[i]!= 0)
			{
				pos = i;
				break;
			}
			for(i = 0,j = pos;i<row +col;i++,j++)
				rel[i] = pro[j]+'0';
			rel[row+col-1]='\0';
			strcpy(result,rel);
			
}