大資料的乘法

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//大資料相乘，具體的演算法思想見c

#define  _CRT_SECURE_NO_WARNINGS  //vs2013去掉安全檢查#include <stdlib.h>#include <string.h>#include <iostream>using namespace std;class big_data{public:    void init_string()    {        cout << "str1 = ";        cin >> str1;        cout << endl;        cout << "str2 = ";        cin >> str2;        cout << endl;    }    char* big_data_multi ()    {        int length_str1 = strlen(str1);        int length_str2 = strlen(str2);        int *pstr3 = (int*)malloc(sizeof(int)*(length_str1+length_str2));        memset(pstr3, 0, sizeof(int)*(length_str1+length_str2));//一定要初始化，否則亂碼        for(int i = 0; i < length_str2; i++)//迴圈累乘相加        {            for(int  j = 0;  j < length_str1; j++)            {                pstr3[i + j + 1] += (str1[j] - ‘0‘) * (str2[i] - ‘0‘);            }        }        for (int i = length_str1 + length_str2 - 1; i >= 0; i--)        {            if(pstr3[i] >= 10)            {                    pstr3[i - 1] += pstr3[i] / 10;                pstr3[i] = pstr3[i]%10;            }        }        int i = 0;        while (pstr3[i] == 0)        {            i++;        }        char *pstr4 = (char*)malloc(sizeof(char)*(length_str1 + length_str2 + 1));        int j = 0;        for(; j < length_str1+length_str2 && i < length_str1+length_str2; j++,i++)        {            pstr4[j] = pstr3[i] + ‘0‘;        }        pstr4[j] = ‘\0‘;        return pstr4;    }private:    char str1[100];    char str2[100];};int main(){    big_data bigdata1;        while(1)    {        cout << endl;        bigdata1.init_string();        cout << "相乘的結果是 ：" << bigdata1.big_data_multi() << endl;    }    system("pause");}

 

大資料的乘法