A × B problem

#include<iostream>
#include<cstring>
#include<queue>
using namespace std;
int a[1000]={0},b[1000]={0},mm[5000]={0};
void daozhi(string s,int a[])//数据倒置存入数组中；
{
  int i,m=0;
  for(i=s.size()-1;i>=0;i--)
  {
    a[m++]=s[i]-‘0‘;
  }
}
void rebuild(string s,string ss,int a[],int b[],int mm[])//乘法的模拟
{
  int n,k,i,j;
  for(i=0;i<s.size();i++)
  {
    n=i;
    for(j=0;j<ss.size();j++)
    {
      k=(mm[n]+(a[i]*b[j])%10)/10;
      mm[n]=(mm[n]+(a[i]*b[j])%10)%10;
      mm[n+1]+=((a[i]*b[j])/10+k);
      n++;
    }
  }
}
int main()
{
  int n,count,i;
  cin>>n;
  count=n;
  while(n--)
  {
    string c,d;
    cin>>c>>d;
    cout<<"Case "<<count-n<<":"<<endl;
    daozhi(c,a);
    daozhi(d,b);
    rebuild(c,d,a,b,mm);
    cout<<c<<" *"<<" "<<d<<" ="<<" ";
    for(i=4999;i>=0;i--)
    {
      if(mm[i]) break;
    }
    for( ;i>=0;i--)
    {
      cout<<mm[i];
    }
    cout<<endl;
    if(n) cout<<endl;
    memset(mm,0,sizeof(mm));
  }
  return 0;
}