大整数处理类（头文件）

/////////////////////integer.h

#include <iostream>

#include <string>

#include <cstring>

#include <math.h>

using namespace std;

#define MAXSIZE   256

/***************************

* @class name: BigInteger

* @author: LoongFee

* @date: 2009-11-03

****************************/

class BigInteger

{

public:

    bool sign;

    char modulus[MAXSIZE];

    int ndigit;

public:

    BigInteger();                      //Defaulted constructor

    BigInteger(const char* a);                //Constructor with a value

    BigInteger(const int& a);

    BigInteger(const BigInteger& another); //Copy constructor

    ~BigInteger();                         //Destructor

 

    BigInteger abs(const BigInteger& another);

    BigInteger mod(const BigInteger& another);

    BigInteger gcd(const BigInteger& another);    //the greatest common divisor

    BigInteger gcd(const BigInteger& a1, const BigInteger& a2);

    BigInteger lcm(const BigInteger& another);    //the least common multiple

    BigInteger lcm(const BigInteger& a1, const BigInteger& a2);

 

    ////Overload operators

    BigInteger& operator = (const BigInteger& another);

    BigInteger& operator = (const string& another);

    BigInteger& operator = (const int& another);

    BigInteger operator + (const BigInteger& another);

    BigInteger& operator += (const BigInteger& another);

    BigInteger operator - (const BigInteger& another);

    BigInteger& operator -= (const BigInteger& another);

    BigInteger operator - ();

    BigInteger operator * (const BigInteger& another);

    BigInteger& operator *= (const BigInteger& another);

    BigInteger operator / (const BigInteger& another);

    BigInteger& operator /= (const BigInteger& another);

    BigInteger operator % (const BigInteger& another);

    BigInteger& operator %= (const BigInteger& another);

    BigInteger& operator ++ ();

    BigInteger& operator -- ();

 

    BigInteger operator ++(int);

    BigInteger operator --(int);

 

    bool operator >= (const BigInteger& another);

    bool operator <= (const BigInteger& another);

    bool operator == (const BigInteger& another);

    bool operator != (const BigInteger& another);

    bool operator > (const BigInteger& another);

    bool operator < (const BigInteger& another);

 

    friend ostream& operator <<(ostream& o, const BigInteger& myInt)

    {

       if(1 == myInt.sign)

           cout<<'-';

       cout<<myInt.modulus;

 

       return o;

    }

    friend istream& operator >>(istream& i, BigInteger& myInt)

    {

       char tmp[MAXSIZE];

       cin>>tmp;

 

       myInt.sign = (tmp[0] == '-') ? 1 : 0;

 

       int pos = myInt.sign;

 

       while('\0' != tmp[pos])

       {

           myInt.modulus[pos - myInt.sign] = tmp[pos++];

       }

 

       myInt.ndigit = (pos - myInt.sign);

       myInt.modulus[myInt.ndigit] = '\0';

 

       return i;

    }

};