c++ 无符号bigint高精度大整数

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c++ 无符号bigint高精度大整数

此代码除了减法和乘法以外均参考了刘汝佳的《算法竞赛入门经典第二版》，亲测DevC++可以编译通过。代码在codevs（ codevs.cn )上通过高精度全部题目。POWERED BY PHANTOM 大神勿喷，希望大家支持！

#include<cstdio>#include<iostream>#include<cmath>#include<algorithm>#include<cstring>#include<string>#include<vector>using namespace std;struct bigint{ // only positive number;    static const int BASE=100000000;    static const int WIDTH=8;    vector<int> s;    //value    bigint(long long num=0){ *this = num;}    bigint operator = (long long num){        s.clear();        do{            s.push_back(num%BASE);            num/=BASE;         }while(num>0);        return *this;    }     bigint operator = (const string& str){        s.clear() ;        int x,len = (str.length()-1)/WIDTH + 1;        for(int i=0;i<len;i++){            int end = str.length() - i*WIDTH;            int start = max(0,end - WIDTH);            sscanf(str.substr(start,end-start).c_str(),"%d",&x);            s.push_back(x);        }        return *this;    }    //input&output    friend ostream& operator << (ostream &out, const bigint& x){        out << x.s.back();        for(int i=x.s.size()-2;i>=0;i--){            char buf[20];            sprintf(buf,"%08d",x.s[i]);            for(int j=0;j<strlen(buf);j++) out << buf[j];        }        return out;    }    friend istream& operator >>(istream &in, bigint& x){        string s;        if(!(in>>s)) return in;        x=s;        return in;    }    //compare    bool operator < (const bigint& b) const {        if(s.size()!=b.s.size()) return s.size() < b.s.size();        for(int i=s.size()-1;i>=0;i++) if(s[i]!=b.s[i]) return s[i] < b.s[i];        return false;//equal    }    bool operator > (const bigint& b) const {return b < *this;}    bool operator <= (const bigint& b) const {return !(b < *this);}    bool operator >= (const bigint& b) const {return !(*this < b);}    bool operator != (const bigint& b) const {return b < *this || *this < b;}    bool operator == (const bigint& b) const {return !(b < *this) && !(*this < b);}    //calculate    bigint operator +(const bigint& b) const {        bigint c;        c.s.clear();        for(int i=0,g=0;;i++){            if(g==0 && i>=s.size() && i>=b.s.size()) break;            int x=g;            if(i<s.size()) x+=s[i];            if(i<b.s.size()) x+=b.s[i];            c.s.push_back(x%BASE);            g = x/BASE;         }        return c;    }    bigint operator +=(const bigint& b){        *this = *this + b;        return *this;    }    bigint operator -(const bigint& b) const {        bigint c;        c.s.clear();        for(int i=0,g=0;;i++){            if(g==0 && i>=s.size() && i>=b.s.size()) break;            int x=g;            if(i<s.size()) x+=s[i];            if(i<b.s.size()) x-=b.s[i];            x+=BASE;            c.s.push_back(x%BASE);            g = x/BASE - 1;         }        return c;    }    bigint operator * (const bigint& b) const {        bigint c;        c.s.clear();        bigint g=0;        for(int i=0;;i++){            if(g.s.size()==0 && i>=s.size()+b.s.size()-1) break;            bigint x;            x.s.clear() ;            for(int j=0;j<g.s.size();j++) x.s.push_back(g.s[j]);             if(i<s.size()+b.s.size()-1){                for(int j = max(0 , i-(int)s.size()+1);j<=min(i,(int)b.s.size()-1);j++){                    bigint t = (long long)b.s[j]*s[i-j];                    x += t;                }              }            c.s.push_back(x.s[0]);            g.s.clear();            if(x.s.size()>1) for(int j=1;j<x.s.size();j++) g.s.push_back(x.s[j]);        }        return c;    }};

以上是全部代码，将bigint封装在一个结构体里面了。支持比较运算符，加减乘运算，支持cin、cout流式输入输出，但是不能把bigint和一般int进行除了赋值以外的运算。
完整的程序代码下载：http://download.csdn.net/detail/a1323933782/9802948
谢谢支持！

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