技術標籤：c++其他c++

#include<iostream>
#include<Cstdlib>
#include<memory>
#include<Cstring>

using namespace std;

#define MAX 1024
/*計算2664乘以4525
2664
4525

          10 30 30 20        5
       4  12 12 8            2
   10 30  30 20              5
8  24 24  16                 4

8  34 58  68 62 38 20

12  0  5   4  6  0  0 
步驟一：乘數從個位挨個乘以被乘數
*/
 


char * change(char * p)//字串反轉
{
	for (int i = 0; i < strlen(p) / 2; i++)
	{
		char temp(0);
		temp = p[i];
		p[i] = p[strlen(p) - 1 - i];
		p[strlen(p) - 1 - i] = temp;
	}
	return p;
}

char * sub(char * beichengshu, char * chengshu)
{
	char * subji=new char[MAX];
	int cslen = strlen(chengshu) - 1,bcslen=
 
 strlen(beichengshu) - 1;
	int si = 0;
	int sum[MAX]{ 0 };
	for (int i = cslen; i>= 0; i--)
	{
		for (int j = bcslen; j >=0 ; j--)
		{
			int temp = (chengshu[i] - 48)*(beichengshu[j] - 48);
				sum[i + j] += temp;//乘數的位挨個與被乘數相乘 8  34 58  68 62 38 20 結果存入陣列
		}
	}
	int k;
	for (k = cslen + bcslen; k >
 
 0; k--)
	{
		subji[si] = (sum[k] % 10)+48;//0  5   4  6  0  0 
		sum[k - 1] += (sum[k] - sum[k] % 10) / 10;//進位
		si++;
	}

	//處理最後一個12
	subji[si++] = (sum[0] % 10) + 48;
	if (((sum[0] - sum[0] % 10) / 10) != 0)
	{
		subji[si] = ((sum[0] - sum[0] % 10) / 10)+48;
		si++;
	}	
	subji[si] = '\0';

	return change(subji);
}

void main()
{
	char  chengshu[MAX];
	char  beichengshu[MAX];
	char  * ji;
	cout << "請輸入被乘數：";
	cin >> beichengshu;
	//beichengshu = "2664";
	cout << "請輸入乘數:";
	cin >> chengshu;
	//chengshu = "4525";

	ji=sub(beichengshu,chengshu );
	cout << "積=:" << ji << endl;

	delete(ji);
	system("pause");
	
}