大整数乘法

#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;
}