[c++]封装高精度运算

高精度运算

此文主要给出了高精度运算的实现细节，并将此封装。

#include <string.h>
#include <iostream>
using namespace std;
#define max 1000
/*
 *  This class implements addition, substraction, multiple operation,
 *  which aim to orient to the big integer.
 *  The detail as follows.
 *  This version are only suitable for positive integer.
 *
 */
class Integer {
   
   
 public:
  /**
   *  The basic part of Integer.
   */
  Integer(string orig) { m_data = orig; }
  friend ostream &operator<<(ostream &out, Integer orig) {
    out << orig.m_data;
    return out;
  }

 public:
  /**
   *  Implement Addition
   *  The basic thought is to transfer the string to array
   *  and operate array so that we can get the answer string.
   *
   *  @param Int_a Integer a
   *  @param Int_b Integer b
   *
   *  @return answer string
   */
  friend string operator+(Integer Int_a, Integer Int_b) {
    size_t a_len = Int_a.m_data.length();
    size_t b_len = Int_b.m_data.length();
    int a_vec[max] = {
  
  0}, b_vec[max] = {
  
  0}, c_vec[max] = {
  
  0};
    /**
     *  Transfer the string to Array
     *  Pay attention to the position of corresponding element in string.
     *  We wanna operate the Integer from the beginning.
     */
    reverse(Int_a.m_data.begin(), Int_a.m_data.end());
    for (int i = 0; i < a_len; i++) {
      a_vec[i] = Int_a.m_data[i] - '0';
    }
    reverse(Int_b.m_data.begin(), Int_b.m_data.end());