输入：两个大整数，以空格分开

输出：大整数的乘积

程序如下：

#include <stdio.h>
#include <string.h>
typedef struct{
	int nums[100];
	int length;
}bigNumber;

bigNumber create(char arr[]){
	bigNumber A;
	int i;
	A.length=strlen(arr);
	for(i=0;i<A.length;i++)
		A.nums[A.length-1-i]=arr[i]-48;
	return A;
}

bigNumber multiply(bigNumber A,bigNumber B){
	bigNumber C;
	int i,j;
	memset(C.nums,0,sizeof(C.nums));
	for(i=0;i<A.length;i++)
		for(j=0;j<B.length;j++)
			C.nums[i+j]+=A.nums[i]*B.nums[j];
	i=0;
	while(i<A.length+B.length-1||C.nums[i]){//这个判断很重要，两个位数分别为a、b的整数相乘，
						//结果只能是a+b-1位或者a+b位
		C.nums[i+1]+=C.nums[i]/10;
		C.nums[i]=C.nums[i]%10;
		i++;
	}
	C.length=i;
	return C;
}

void print(bigNumber C){
	int i;
	for(i=C.length-1;i>=0;i--)
		printf("%d",C.nums[i]);
	putchar('\n');
}

int main(){
	char strA[100],strB[100];
	bigNumber numA,numB,numC;
	while(scanf("%s%s",strA,strB)!=EOF){
		numA=create(strA);
		numB=create(strB);
		numC=multiply(numA,numB);
		print(numC);
	}
	return 0;
}