一个大数运算类-白红宇

#include <stdio.h>

#include <math.h>

#include <iostream>

using namespace std;

class decnum

{

friend decnum pow(const decnum& x, int n);

friend decnum root(const decnum& x, int n);

friend decnum div(const decnum& x, const decnum& y, decnum& r);

friend decnum abs(const decnum& x);

friend bool operator==(const decnum& x, const decnum&y);

friend bool operator!=(const decnum& x, const decnum&y);

friend bool operator>(const decnum& x, const decnum&y);

friend bool operator<(const decnum& x, const decnum&y);

friend bool operator>=(const decnum& x, const decnum&y);

friend bool operator<=(const decnum& x, const decnum&y);

friend ostream& operator<<(ostream&os, const decnum& x);

public:

decnum() : cap(0), num(0), sign(0), val(NULL) { }

decnum(const char *v, int n)

{

int i, j,k;

val = new char[n];

if(v[0] == '-')

{

sign = 1;

v++;

n--;

}

else

{

sign = 0;

if(v[0] == '+')

v++;

}

for(i = 0; i < n && v[i] == '0'; i++);

for (j=0,k=n-1;k>=i;--k,++j)

{

if (v[k]>='0' && v[k]<='9')

{

val[j] = v[k]-'0';

}

else

break;

}

num = j;

cap = n;

}

decnum(const decnum& x)

{

val = new char[x.num];

memcpy(val, x.val, x.num);

sign = x.sign;

num = x.num;

cap = x.num;

}

decnum(int x)

{

if(x==0)

{

cap = num = 0;

val = NULL;

return;

}

if(x < 0)

{

sign = 1;

x = -x;

}

else

sign = 0;

char temp[20];

sprintf(temp, "%d", x);

int n = strlen(temp);

num = cap = n;

val = new char[n];

for(int i=0; i<n; i++)

val[i] = temp[n-1-i] - '0';

}

decnum(long long x)

{

if(x==0)

{

cap = num = 0;

val = NULL;

return;

}

if(x < 0)

{

sign = 1;

x = -x;

}

else

sign = 0;

char temp[20];

sprintf(temp, "%lld", x);

int n = strlen(temp);

num = cap = n;

val = new char[n];

for(int i=0; i<n; i++)

val[i] = temp[n-1-i] - '0';

}

~decnum() { delete[] val; }

int size() const { return num; }

decnum& operator=(const decnum& x)

{

if (this != &x)

{

if(cap < x.num)

{

delete[] val;

val = new char[x.num];

cap = x.num;

}

memcpy(val, x.val, x.num);

num = x.num;

sign = x.sign;

}

return *this;

}

decnum& operator=(int x)

{

*this = decnum(x);

return *this;

}

decnum& operator=(long long x)

{

*this = decnum(x);

return *this;

}

decnum& abs()

{

sign = 0;

return *this;

}

decnum& operator+=(const decnum& x);

decnum& operator-=(const decnum& x);

decnum& operator*=(const decnum& x);

decnum& operator/=(const decnum& x);

decnum& operator%=(const decnum& x);

decnum operator+(const decnum& x) const;

decnum operator-(const decnum& x) const;

decnum operator*(const decnum& x) const;

decnum operator/(const decnum& x) const;

decnum operator%(const decnum& x) const;

bool ispow(int n, decnum& r) const;

bool ispow() const;

private:

int cap;

int num;

int sign;

char *val;

private:

char root_1(int n);

decnum& absadd(const decnum& x);

decnum& abssub(const decnum& x);

bool absge(const decnum& x);

};

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实现代码

大数类实现代码

测试代码：

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#include <iostream>

#include <string>

using namespace std;

#include "decnum.h"

int main()

{

decnum x, y, r;

string line;

size_t n = 0;

cout << "input x:" << endl;

getline(cin,line);

x = decnum(line.c_str(), line.length());

cout << "input y:" << endl;

getline(cin,line);

y = decnum(line.c_str(), line.length());

cout << "x = " << x << endl;

cout << "y = " << y << endl;

cout << "x * y =" << x * y << endl;

cout << "x / y =" << x / y << endl;

cout << "x % y =" << x % y << endl;

cout << "div(x, y) =" << div(x , y, r) << endl;

cout << "mod(x, y) =" << r << endl;

cout << "y ^ 2 =" << pow(y, 2) << endl;

cout << "x ^ 1/2 =" << root(x, 2) << endl;

cout << "x is pow = " << x.ispow() << endl;

system("pause");

return 0;

}

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本文转自Phinecos(洞庭散人)博客园博客，原文链接：http://www.cnblogs.com/phinecos/archive/2008/11/12/1332344.html，如需转载请自行联系原作者