大整数乘法

来源：互联网发布：c语言实验报告答案编辑：程序博客网时间：2024/05/29 17:48
#include<stdio.h>#include<stdlib.h>#include<string.h>char result[200];void mulStr(char *str, char *one, char* two){    char *str1 = one;    char *str2 = two;    if(!strcmp(str1,"0")||!strcmp(str2,"0"))    {        strcpy(str,"0");        return;    }    bool sinal = true;    int len1 = strlen(str1);    int len2 = strlen(str2);    if(*str1=='-')    {        len1--;        str1++;         sinal = !sinal;    }    if(*str2=='-')    {        len2--;        str2++;         sinal = !sinal;    }    int i,j;    int carry=0, out=0,addition;       char *result = str;    memset(result,'0',len1+len2+1);    for(i=len1-1;i>=0;i--)    {        for(j=len2-1;j>=0;j--)        {            out = (*(str1+i)-'0')*(*(str2+j)-'0')+carry+*(str+len1+len2-i-j-2)-'0';            *(str+len1+len2-i-j-2) = out%10 + '0';            carry =  out/10;        }        *(str+len1-i+len2-1) = carry +'0';          carry = 0;    }    char *pend = result + len1 + len2 -1;    if(*pend=='0')    {        if(!sinal)        {            *pend = '-';            *(pend+1) = 0;            pend++;        }        else        {            *pend = 0;            pend--;        }    }    else    {        if(!sinal)        {            *(pend+1) = '-';            *(pend+2) = 0;            pend++;        }        else        {            *(pend+1)=0;        }    }    char ch;    while(result<pend)    {         ch = *pend;        *pend = *result;        *result = ch;        result++;        pend--;    }    return ;}int main(){    char str1[100];    char str2[100];    char result[200];    while(~scanf("%s %s", str1,str2))    {        mulStr(result,str1,str2);        printf("%s\n",result);    }    return 0;}
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