接1
cata &cata::operator +(const cata &y)
{
    int len_x=length(),len_y=y.length();
    int len_max=len_x>len_y? len_x:len_y,len_min=len_x<len_y? len_x:len_y;
    int *result=new int[len_max+1];             //result存放高精度加法结果
    for(int i=0;i<len_max+1;i++)                //将result全部置0
    {
        result[i]=0;
    }
    int carry=0,temp_1,temp_2;                  //carry为进位
    for(i=0;i<len_min;i++)                      //按位加,分两步做
    {
        temp_2=temp_1=data[i]+y.data[i]+carry;
        carry=temp_1/10;
        if(carry)
            result[i]=temp_2%10;
        else result[i]=temp_2;
    }
    if(len_x>=len_y)
    {
        for(i=len_min;i<len_max;i++)
        {
            temp_2=temp_1=data[i]+result[i]+carry;
            carry=temp_1/10;
            if(carry)
            {
                result[i]=temp_2%10;
            }
            else
            {
                result[i]=temp_2;
            }
        }
    }
    else
    {
        for(i=len_min;i<len_max;i++)
        {
            temp_2=temp_1=y.data[i]+result[i]+carry;
            carry=temp_1/10;
            if(carry)
            {
                result[i]=temp_2%10;
            }
            else
            {
                result[i]=temp_2;
            }
        }
    }
    if(carry)
    {
        result[len_max]=carry;
        n=len_max+1;
    }
    else
    {
        n=len_max;
    }
    int *temp=result;                            //指针的交换
    result=data;                                 
    data=temp;
    delete [] result;
    return *this;
}///:p

cata &cata::operator -(const cata &y)
{
    int len_max=length(),len_y=y.length();
    int *result=new int [len_max];               //result用于存放高精度减法的结果
    if(NULL==result)
    {
        cout<<"the error take place in -"<<endl;
        exit(1);
    }
    for(int i=0;i<len_max;i++)
    {
        result[i]=0;
    }
    int borrow=0,temp;                            //borrow位借
    int displace=y.displacement;
    for(i=0;i<len_y;i++)                         //按位减,分两步做
    {
        temp=data[i]+10-y.data[i+displace]-borrow;
        if(temp>=10)
        {
            temp=temp-10;
            borrow=0;
        }
        else
        {
            borrow=1;
        }
        result[i]=temp;
    }
    for(int j=len_y;j<len_max;j++)
    {
        temp=data[j]+10-result[j]-borrow;
        if(temp>=10)
        {
            temp=temp-10;
            borrow=0;
        }
        else
        {
            borrow=1;
        }
        result[j]=temp;
    }
    n=len_max;
    i=1;
    while(result[n-i]==0&&i<n)                         //由于减法会在高位产生0,i的回溯相当于去掉无用的高位0
    {
        i++;
    }
    n=n-i+1;                                           //i回溯后,重新计算n
    int *temp_sub=result;                              //交换指针,保证结果实在*this对象中
    result=data;
    data=temp_sub;
    delete [] result;
    return *this;
}///:p

cata &cata::operator *(const cata &y)
{
    int len_x=length(),len_y=y.length();
    int len_z=len_x+len_y;
    int *result=new int [len_z];                       //result存放高精度*的结果
    int *temp=new int [len_z];
    if(NULL==result||NULL==temp)
    {
        cout<<"the error take place in *"<<endl;
        exit(1);
    }
    for(int j=0;j<len_z;j++)
    {
        result[j]=0;
    }    
    int carry,temp1,temp2;                            //carry为进位
    for(j=0;j<len_y;j++)                              //模拟手工方法,实现乘法
    {
        for(int i=0;i<len_z;i++)
        {
            temp[i]=0;
        }
        carry=0;
        for(i=0;i<len_x;i++)
        {
            temp2=temp1=data[i]*y.data[j]+carry;
            carry=temp1/10;
            if(carry)
            {
                temp[i+j]=temp2%10;
            }
            else
            {
                temp[i+j]=temp2;
            }
        }
        if(carry)
        {
            temp[len_x+j]=carry;
        }
        int carry_add=0,temp1_add,temp2_add;           //乘法中的加法
        for(i=0;i<len_z;i++)
        {
            temp2_add=temp1_add=temp[i]+result[i]+carry_add;
            carry_add=temp1_add/10;
            if(carry_add)
            {
                result[i]=temp2_add%10;
            }
            else
            {
                result[i]=temp2_add;
            }
        }
    }
    this->n=len_z;
    int i=1;
    while(result[n-i]==0&&i<n)
    {
        i++;
    }
    n=n-i+1;
    int *temp_change=result;                           //交换指针
    result=data;
    data=temp_change;
    delete [] result;
    return *this;
}///:p