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 BigInteger public: static const BigInteger ZERO; static const BigInteger ONE; static const BigInteger TEN; }; // BigInteger.cpp const 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) ); 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 operators 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 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 operators BigInteger 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
