C++ 大数模板 持续更新中...

第一次更新博客(2017/5/3)...

目前只有正整数的加减法和乘法。

使用STL里的string来存大数字符，真的是无比好用...

加法...

减法...

乘法...

然后是完整代码...

#include <iostream>#include <string>#include <vector>using namespace std;string sum(string ans, string b);string subtract(string ans, string b);string multiply(string a, string b);int main(){string a, b;int c;while(cin >> a >> b){cin >> c;if(c == 0) cout << sum(a, b) << endl;if(c == 1) cout << subtract(a, b) << endl;if(c == 2) cout << multiply(a, b) << endl;}return 0;}string sum(string ans, string b){if(ans.length() < b.length()) ans.swap(b);for(int i = ans.length()-1, j = b.length()-1; i >= 0; --i, --j){ans[i] = ans[i] + (j >= 0? b[j]-'0': 0); if(ans[i] > '9'){ans[i] -= 10;if(i > 0) ++ans[i-1];else ans.insert(0, "1");}}return ans;}string subtract(string ans, string b){if(ans.length() < b.length() || ans.length() == b.length() && ans < b) ans.swap(b);for(int i = ans.length()-1, j = b.length()-1; i >= 0; --i, --j){ans[i] = ans[i] - (j >= 0? b[j]-'0': 0);if(ans[i] < '0'){ans[i] += 10;--ans[i-1];}}while(ans.length() && ans[0] == '0') ans.erase(ans.begin());if(ans.empty()) ans = "0";return ans;}string multiply(string a, string b){int m = a.length(), n = b.length();//一个m位数乘以一个n位数，结果至少是m+n-1位vector<int> tmp(m+n-1);//vector预分配内存，初始值为0//进行笛卡尔乘积for(int i = 0; i < m; ++i)//string 0位为高位for(int j = 0; j < n; ++j)tmp[i+j] += (a[i]-'0')*(b[j]-'0');for(int i = tmp.size()-1; i > 0; --i){//由低位到高位进位tmp[i-1] += tmp[i]/10;tmp[i] %= 10;}while(tmp[0] > 9){//最高位仍能进位tmp.insert(tmp.begin(), tmp[0]/10);tmp[1] %= 10;}string ans;for(int i = 0, len = tmp.size(); i < len; ++i) ans += tmp[i] + '0';if(ans[0] == '0') return "0";return ans;}

待更新...继续加油~

2017/07/23 (完整模板)

#include <iostream>#include <vector>#include <string>#include <queue>using namespace std;class DividedByZeroException {};class BigInteger{private:    vector<char> digits;    bool sign;          // true for positive, false for negitive    void trim();        // remove zeros in tail, but if the value is 0, keep only one:)public:    BigInteger(int);    // construct with a int integer    BigInteger(string&) ;    BigInteger();    BigInteger (const BigInteger&);    BigInteger operator=(const BigInteger& op2);    BigInteger abs() const;    BigInteger pow(int a);    //binary operators    friend BigInteger operator+=(BigInteger&,const BigInteger&);    friend BigInteger operator-=(BigInteger&,const BigInteger&);    friend BigInteger operator*=(BigInteger&,const BigInteger&);    friend BigInteger operator/=(BigInteger&,const BigInteger&) throw(DividedByZeroException);    friend BigInteger operator%=(BigInteger&,const BigInteger&) throw(DividedByZeroException);    friend BigInteger operator+(const BigInteger&,const BigInteger&);    friend BigInteger operator-(const BigInteger&,const BigInteger&);    friend BigInteger operator*(const BigInteger&,const BigInteger&);    friend BigInteger operator/(const BigInteger&,const BigInteger&) throw(DividedByZeroException);    friend BigInteger operator%(const BigInteger&,const BigInteger&) throw(DividedByZeroException);    //uniary operators    friend BigInteger operator-(const BigInteger&);   //negative    friend BigInteger operator++(BigInteger&);        //++v    friend BigInteger operator++(BigInteger&,int);    //v++    friend BigInteger operator--(BigInteger&);        //--v    friend BigInteger operator--(BigInteger&,int);    //v--    friend bool operator>(const BigInteger&,const BigInteger&);    friend bool operator<(const BigInteger&,const BigInteger&);    friend bool operator==(const BigInteger&,const BigInteger&);    friend bool operator!=(const BigInteger&,const BigInteger&);    friend bool operator>=(const BigInteger&,const BigInteger&);    friend bool operator<=(const BigInteger&,const BigInteger&);    friend ostream& operator<<(ostream&,const BigInteger&);    //print the BigInteger    friend istream& operator>>(istream&, BigInteger&);         // input the BigIntegerpublic:    static const BigInteger ZERO;    static const BigInteger ONE;    static const BigInteger TEN;};// BigInteger.cppconst BigInteger BigInteger::ZERO=BigInteger(0);const BigInteger BigInteger::ONE =BigInteger(1);const BigInteger BigInteger::TEN =BigInteger(10);BigInteger::BigInteger(){    sign=true;}BigInteger::BigInteger(int val) // construct with a int integer{    if (val >= 0)        sign = true;    else    {        sign = false;        val *= (-1);    }    do    {        digits.push_back( (char)(val%10) );        val /= 10;    }    while ( val != 0 );}BigInteger::BigInteger(string& def){    sign=true;    for ( string::reverse_iterator iter = def.rbegin() ; iter < def.rend();  iter++)    {        char ch = (*iter);        if (iter == def.rend()-1)        {            if ( ch == '+' )                break;            if(ch == '-' )            {                sign = false;                break;            }        }        digits.push_back( (char)((*iter) - '0' ) );    }    trim();}void BigInteger::trim(){    vector<char>::reverse_iterator iter = digits.rbegin();    while(!digits.empty() && (*iter) == 0)    {        digits.pop_back();        iter=digits.rbegin();    }    if( digits.size()==0 )    {        sign = true;        digits.push_back(0);    }}BigInteger::BigInteger(const BigInteger& op2){    sign = op2.sign;    digits=op2.digits;}BigInteger BigInteger::operator=(const BigInteger& op2){    digits = op2.digits;    sign = op2.sign;    return (*this);}BigInteger BigInteger::abs() const{    if(sign)  return *this;    else      return -(*this);}BigInteger BigInteger::pow(int a){    BigInteger res(1);    for(int i=0; i<a; i++)        res*=(*this);    return res;}//binary operatorsBigInteger operator+=(BigInteger& op1,const BigInteger& op2){    if( op1.sign == op2.sign )    {        //只处理相同的符号的情况，异号的情况给-处理        vector<char>::iterator iter1;        vector<char>::const_iterator iter2;        iter1 = op1.digits.begin();        iter2 = op2.digits.begin();        char to_add = 0;        //进位        while ( iter1 != op1.digits.end() && iter2 != op2.digits.end())        {            (*iter1) = (*iter1) + (*iter2) + to_add;            to_add = ((*iter1) > 9);    // 大于9进一位            (*iter1) = (*iter1) % 10;            iter1++;            iter2++;        }        while ( iter1 != op1.digits.end() )        {            (*iter1) = (*iter1) + to_add;            to_add = ( (*iter1) > 9 );            (*iter1) %= 10;            iter1++;        }        while ( iter2 != op2.digits.end() )        {            char val = (*iter2) + to_add;            to_add = (val > 9) ;            val %= 10;            op1.digits.push_back(val);            iter2++;        }        if( to_add != 0 )            op1.digits.push_back(to_add);        return op1;    }    else    {        if (op1.sign)            return op1 -= (-op2);        else            return op1= op2 - (-op1);    }}BigInteger operator-=(BigInteger& op1,const BigInteger& op2){    if( op1.sign == op2.sign )    {        //只处理相同的符号的情况，异号的情况给+处理        if(op1.sign)        {            if(op1 < op2)  // 2 - 3                return  op1=-(op2 - op1);        }        else        {            if(-op1 > -op2)  // (-3)-(-2) = -(3 - 2)                return op1=-((-op1)-(-op2));            else             // (-2)-(-3) = 3 - 2                return op1= (-op2) - (-op1);        }        vector<char>::iterator iter1;        vector<char>::const_iterator iter2;        iter1 = op1.digits.begin();        iter2 = op2.digits.begin();        char to_substract = 0;  //借位        while ( iter1 != op1.digits.end() && iter2 != op2.digits.end())        {            (*iter1) = (*iter1) - (*iter2) - to_substract;            to_substract = 0;            if( (*iter1) < 0 )            {                to_substract=1;                (*iter1) += 10;            }            iter1++;            iter2++;        }        while ( iter1 != op1.digits.end() )        {            (*iter1) = (*iter1) - to_substract;            to_substract = 0;            if( (*iter1) < 0 )            {                to_substract=1;                (*iter1) += 10;            }            else break;            iter1++;        }        op1.trim();        return op1;    }    else    {        if (op1 > BigInteger::ZERO)            return op1 += (-op2);        else            return op1 = -(op2 + (-op1));    }}BigInteger operator*=(BigInteger& op1,const BigInteger& op2){    BigInteger result(0);    if (op1 == BigInteger::ZERO || op2==BigInteger::ZERO)        result = BigInteger::ZERO;    else    {        vector<char>::const_iterator iter2 = op2.digits.begin();        while( iter2 != op2.digits.end() )        {            if(*iter2 != 0)            {                deque<char> temp(op1.digits.begin() , op1.digits.end());                char to_add = 0;                deque<char>::iterator iter1 = temp.begin();                while( iter1 != temp.end() )                {                    (*iter1) *= (*iter2);                    (*iter1) += to_add;                    to_add = (*iter1) / 10;                    (*iter1) %= 10;                    iter1++;                }                if( to_add != 0)                    temp.push_back( to_add );                int num_of_zeros = iter2 - op2.digits.begin();                while(  num_of_zeros--)                    temp.push_front(0);                BigInteger temp2;                temp2.digits.insert( temp2.digits.end() , temp.begin() , temp.end() );                temp2.trim();                result = result + temp2;            }            iter2++;        }        result.sign = ( (op1.sign && op2.sign) || (!op1.sign && !op2.sign) );    }    op1 = result;    return op1;}BigInteger operator/=(BigInteger& op1 , const BigInteger& op2 ) throw(DividedByZeroException){    if( op2 == BigInteger::ZERO )        throw DividedByZeroException();    BigInteger t1 = op1.abs(), t2 = op2.abs();    if ( t1 < t2 )    {        op1 = BigInteger::ZERO;        return op1;    }    //现在 t1 > t2 > 0    //只需将 t1/t2的结果交给result就可以了    deque<char> temp;    vector<char>::reverse_iterator iter = t1.digits.rbegin();    BigInteger temp2(0);    while( iter != t1.digits.rend() )    {        temp2 = temp2 * BigInteger::TEN + BigInteger( (int)(*iter) );        char s = 0;        while( temp2 >= t2 )        {            temp2 = temp2 - t2;            s = s + 1;        }        temp.push_front( s );        iter++;    }    op1.digits.clear();    op1.digits.insert( op1.digits.end() , temp.begin() , temp.end() );    op1.trim();    op1.sign = ( (op1.sign && op2.sign) || (!op1.sign && !op2.sign) );    return op1;}BigInteger operator%=(BigInteger& op1,const BigInteger& op2) throw(DividedByZeroException){    return op1 -= ((op1 / op2)*op2);}BigInteger operator+(const BigInteger& op1,const BigInteger& op2){    BigInteger temp(op1);    temp += op2;    return temp;}BigInteger operator-(const BigInteger& op1,const BigInteger& op2){    BigInteger temp(op1);    temp -= op2;    return temp;}BigInteger operator*(const BigInteger& op1,const BigInteger& op2){    BigInteger temp(op1);    temp *= op2;    return temp;}BigInteger operator/(const BigInteger& op1,const BigInteger& op2) throw(DividedByZeroException){    BigInteger temp(op1);    temp /= op2;    return temp;}BigInteger operator%(const BigInteger& op1,const BigInteger& op2) throw(DividedByZeroException){    BigInteger temp(op1);    temp %= op2;    return temp;}//uniary operatorsBigInteger operator-(const BigInteger& op)    //negative{    BigInteger temp = BigInteger(op);    temp.sign = !temp.sign;    return temp;}BigInteger operator++(BigInteger& op)     //++v{    op += BigInteger::ONE;    return op;}BigInteger operator++(BigInteger& op,int x)   //v++{    BigInteger temp(op);    ++op;    return temp;}BigInteger operator--(BigInteger& op)     //--v{    op -=  BigInteger::ONE;    return op;}BigInteger operator--(BigInteger& op,int x)   //v--{    BigInteger temp(op);    --op;    return temp;}bool operator<(const BigInteger& op1,const BigInteger& op2){    if( op1.sign != op2.sign )        return !op1.sign;    else    {        if(op1.digits.size() != op2.digits.size())            return (op1.sign && op1.digits.size()<op2.digits.size())            || (!op1.sign && op1.digits.size()>op2.digits.size());        vector<char>::const_reverse_iterator iter1,iter2;        iter1 = op1.digits.rbegin();        iter2 = op2.digits.rbegin();        while( iter1 != op1.digits.rend() )        {            if(  op1.sign &&  *iter1 < *iter2 ) return true;            if(  op1.sign &&  *iter1 > *iter2 ) return false;            if( !op1.sign &&  *iter1 > *iter2 ) return true;            if( !op1.sign &&  *iter1 < *iter2 ) return false;            iter1++;            iter2++;        }        return false;    }}bool operator==(const BigInteger& op1,const BigInteger& op2){    if( op1.sign != op2.sign  || op1.digits.size() != op2.digits.size() )        return false;    vector<char>::const_iterator iter1,iter2;    iter1 = op1.digits.begin();    iter2 = op2.digits.begin();    while( iter1!= op1.digits.end() )    {        if( *iter1 != *iter2 )  return false;        iter1++;        iter2++;    }    return true;}bool operator!=(const BigInteger& op1,const BigInteger& op2){    return !(op1==op2);}bool operator>=(const BigInteger& op1,const BigInteger& op2){    return (op1>op2) || (op1==op2);}bool operator<=(const BigInteger& op1,const BigInteger& op2){    return (op1<op2) || (op1==op2);}bool operator>(const BigInteger& op1,const BigInteger& op2){    return !(op1<=op2);}ostream& operator<<(ostream& stream,const BigInteger& val)//print the BigInteger{    if (!val.sign)        stream << "-";    for ( vector<char>::const_reverse_iterator iter = val.digits.rbegin(); iter != val.digits.rend(); iter++)        stream << (char)((*iter) + '0');    return stream;}istream& operator>>(istream& stream, BigInteger& val){    //Input the BigInteger    string str;    stream >> str;    val=BigInteger(str);    return stream;}int main(){    BigInteger bt = 100;    cout << bt << endl;    bt = 101;    cout << bt << endl;        BigInteger a = BigInteger(30);cout << a << endl; string s = "-33333333";BigInteger x = BigInteger(s);cout << x << endl;cout << x.abs() << endl;BigInteger q = a;cout << q << endl;cout << q.pow(2) << endl;cout << q.TEN << endl;         BigInteger arry[105];    arry[0] = 4831;    cout << arry[0] << endl;        BigInteger p;while(cin >> p) break;//可读至文件结束 cout << "操作：" << endl;cout << "运算：+ - * / %";cout << "+= -= *= /= %=";cout << "自运算：-- ++"; cout << "输入>> 输出<<";cout << "比较：> < >= <= == !=";     return 0;}

Copy自：链接