C++大数板子

C++大数板子

使用样例在主函数里看就好，必要的运算符都重载了。

#include <iostream>
using namespace std;
const int maxn=;/*精度位数,自行调整*/
//1.如果需要控制输出位数的话，在str()里面把len调成需要的位数
//2.很大的位数是会re的，所以如果是幂运算的话，如 计算x^p的位数n, n=p*log(10)x+1;(注意要加一）
//3.还可以加上qmul，取模的过程也就是str()，c_str()再搞一次
class bign{
    friend istream& operator>>(istream&,bign&);
    friend ostream& operator<<(ostream&,const bign&);
    friend bign operator+(const bign&,const bign&);
    friend bign operator+(const bign&,int&);
    friend bign operator*(const bign&,const bign&);
    friend bign operator*(const bign&,int&);
    friend bign operator-(const bign&,const bign&);
    friend bign operator-(const bign&,int&);
    friend bign operator/(const bign&,const bign&);
    friend bign operator/(const bign&,int&);
    friend bign operator%(const bign&,const bign&);
    friend bign operator%(const bign&,int&);
    friend bool operator<(const bign&,const bign&);
    friend bool operator>(const bign&,const bign&);
    friend bool operator<=(const bign&,const bign&);
    friend bool operator>=(const bign&,const bign&);
    friend bool operator==(const bign&,const bign&);
    friend bool operator!=(const bign&,const bign&);

private://如果想访问len,改成public
    int len,s[maxn];
public:
    bign(){
        memset(s,,sizeof(s));
        len=;
    }
    bign operator=(const char* num){
        int i=,ol;
        ol=len=strlen(num);
        while(num[i++]==''&&len>)
            len--;
        memset(s,,sizeof(s));
        for(i=; i<len; i++)
            s[i]=num[ol-i-]-'';
        return *this;
    }
    bign operator=(int num){
        char s[maxn];
        sprintf(s,"%d",num);
        *this=s;
        return *this;
    }
    bign(int num){
        *this=num;
    }
    bign(const char* num){
        *this=num;
    }
    string str() const{
        string res="";
        for(int i=; i<len; i++)
            res=char(s[i]+'')+res;
        if(res=="")
            res="";
        return res;
    }
};
bool operator<(const bign& a,const bign& b){
    int i;
    if(a.len!=b.len)
        return a.len<b.len;
    for(i=a.len-; i>=; i--)
        if(a.s[i]!=b.s[i])
            return a.s[i]<b.s[i];
    return false;
}
bool operator>(const bign& a,const bign& b){
    return b<a;
}
bool operator<=(const bign& a,const bign& b){
    return !(a>b);
}
bool operator>=(const bign& a,const bign& b){
    return !(a<b);
}
bool operator!=(const bign& a,const bign& b){
    return a<b||a>b;
}
bool operator==(const bign& a,const bign& b){
    return !(a<b||a>b);
}
bign operator+(const bign& a,const bign& b){
    int up=max(a.len,b.len);
    bign sum;
    sum.len=;
    for(int i=,t=;t||i<up; i++)
    {
        if(i<a.len)
            t+=a.s[i];
        if(i<b.len)
            t+=b.s[i];
        sum.s[sum.len++]=t%;
        t/=;
    }
    return sum;
}
bign operator+(const bign& a,int& b){
    bign c=b;
    return a+c;
}
bign operator*(const bign& a,const bign& b){
    bign res;
    for(int i=; i<a.len; i++)
    {
        for(int j=; j<b.len; j++)
        {
            res.s[i+j]+=(a.s[i]*b.s[j]);
            res.s[i+j+]+=res.s[i+j]/;
            res.s[i+j]%=;
        }
    }
    res.len=a.len+b.len;
    while(res.s[res.len-]==&&res.len>)
        res.len--;
    if(res.s[res.len])
        res.len++;
    return res;
}
bign operator*(const bign& a,int& b){
    bign c=b;
    return a*c;
}
//只支持大数减小数
bign operator-(const bign& a,const bign& b){
    bign res;
    int len=a.len;
    for(int i=; i<len; i++)
    {
        res.s[i]+=a.s[i]-b.s[i];
        if(res.s[i]<)
        {
            res.s[i]+=;
            res.s[i+]--;
        }
    }
    while(res.s[len-]==&&len>)
        len--;
    res.len=len;
    return res;
}
bign operator-(const bign& a,int& b){
    bign c=b;
    return a-c;
}
bign operator/(const bign& a,const bign& b){
    int i,len=a.len;
    bign res,f;
    for(i=len-; i>=; i--)
    {
        f=f*;
        f.s[]=a.s[i];
        while(f>=b)
        {
            f=f-b;
            res.s[i]++;
        }
    }
    while(res.s[len-]==&&len>)
        len--;
    res.len=len;
    return res;
}
bign operator/(const bign& a,int& b){
    bign c=b;
    return a/c;
}
bign operator%(const bign& a,const bign& b){
    int len=a.len;
    bign f;
    for(int i=len-; i>=; i--)
    {
        f=f*;
        f.s[]=a.s[i];
        while(f>=b)
            f=f-b;
    }
    return f;
}
bign operator%(const bign& a,int& b){
    bign c=b;
    return a%c;
}
bign& operator+=(bign& a,const bign& b){
    a=a+b;
    return a;
}
bign& operator-=(bign& a,const bign& b)
{
    a=a-b;
    return a;
}
bign& operator*=(bign& a,const bign& b){
    a=a*b;
    return a;
}
bign& operator/=(bign& a,const bign& b){
    a=a/b;
    return a;
}
bign& operator++(bign& a){
    a=a+;
    return a;
}
bign& operator++(bign& a,int){
    bign t=a;
    a=a+;
    return t;
}
bign& operator--(bign& a){
    a=a-;
    return a;
}
bign& operator--(bign& a,int){
    bign t=a;
    a=a-;
    return t;
}
istream& operator>>(istream &in,bign& x){
    string s;
    in>>s;
    x=s.c_str();
    return in;
}
ostream& operator<<(ostream &out,const bign& x){
    out<<x.str();
    return out;
}
int main(){
    bign a;
    bign b;
    cin>>a>>b;
    cout<<a%b<<endl;
    cout<<a-b<<endl;
    return ;
}