Two big numbers to multiply

最新推荐文章于 2022-11-18 02:21:12 发布

alanTuringJen

最新推荐文章于 2022-11-18 02:21:12 发布

阅读量364

点赞数 1

CC 4.0 BY-SA版权

分类专栏： c语言文章标签： C语言 algorithm-design

本文链接：https://blog.youkuaiyun.com/alanTuringjen/article/details/72797644

c语言专栏收录该内容

3 篇文章

订阅专栏

本文介绍了一种处理大数乘法的方法，通过定义一个足够大的数组来存储每一位数字，并使用逐位相乘的方式实现了两个大数之间的乘法运算。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Description：

Input two numbers (A and B) which are overflow, then output answer (A * B).
My code is as follows:

// bigNumberToMultiply.cpp
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>
#include <time.h>
#include <math.h>
#define MAX_BIT 100 // The most bits is changed by changing MAX_BIT
#define subtract48(a) a -= 48
#define plus48(a) a += 48

int main()
{
    // Initial arraies to store big number.
    char num1[MAX_BIT], num2[MAX_BIT], numTemp[MAX_BIT][MAX_BIT], numFinal[2 * MAX_BIT + 2];
    memset(num1, 0, sizeof(num1));
    memset(num2, 0, sizeof(num2));
    memset(*numTemp, 0, sizeof(numTemp));
    memset(numFinal, 0, sizeof(numFinal));
    int i = 0, j = 0, k = 0;
    gets(num1);
    gets(num2);
    while (num1[i++]){
        subtract48(num1[i - 1]);
    }
    while (num2[j++]){
        subtract48(num2[j - 1]);
    }
    int bit1 = i - 2, bit2 = j - 2;
    // Multiply by each bit
    int more = 0;
    for (i = bit2; i >= 0; i--){
        for (j = bit1; j >= 0; j--){
            numTemp[bit2 - i][bit1 - j] = (num1[j] * num2[i] + more) % 10;
            more = (num1[j] * num2[i] + more) / 10;
        }
        numTemp[bit2 - i][bit1 - j] = more;
        more = 0;
    }
    // To get final answer to numFinal
    int maxBit, currentBit; //currentBit is for numFinal
    for (i = 0; i <= bit2; i++){
        j = MAX_BIT;
        while (!numTemp[i][--j] && j >= 0);
        maxBit = j;
        if (maxBit != 0){
            for (j = 0; j <= maxBit; j++){
                currentBit = j + i;
                numFinal[currentBit] += numTemp[i][j];
                while (numFinal[currentBit++] > 9){
                    numFinal[currentBit] += numFinal[currentBit - 1] / 10;
                    numFinal[currentBit - 1] %= 10;
                }
            }
        }
    }
    i = 2 * MAX_BIT + 2;
    while (!numFinal[--i]);
    for (i; i >= 0; i--){
        plus48(numFinal[i]);
        printf ("%c", numFinal[i]);
    }
    putchar ('\n');
    system("pause");
    return 0;
}