c++实现的任意大整数类，是c++新手练手的良好材料 定义可处理任意大的正整数类LongLongInt，用一个动态字符数组存放任

//Methods of LongLongint #include "LongLongint.h" LongLongint::LongLongint(const char* ch) { len = strlen(ch); data = new int[len]; for(int i = len - 1; i >= 0; --i) data[i] = ch[len - 1 -i] - '0'; } LongLongint::LongLongint() { data = new int[1]; data[0] = 0; } LongLongint::LongLongint(const LongLongint & num) { len = num.len; data = new int[len]; for(int i = 0; i < len; ++i) data[i] = num.data[i]; } LongLongint::~LongLongint() { delete []data; } LongLongint LongLongint::add(const LongLongint& num2) { LongLongint result; delete []result.data; //delete the initialize space bool islonger = (len >= num2.len); result.len = islonger ? len : num2.len; result.data = new int[result.len]; int shorter_len = (not islonger) ? len : num2.len; for (int i = 0; i < shorter_len ; ++i) //add the number on the same place result.data[i] = data[i] + num2.data[i]; for(int i = shorter_len; i < result.len; ++i) //add the rest of number result.data[i] = islonger ? data[i] : num2.data[i]; for (int i = 0; i < result.len - 1; ++i) //carry the number if(result.data[i] > 9) { result.data[i] %= 10; ++result.data[i+1]; } if(result.data[result.len - 1] < 10) //no need to carry return result; else //the length of the array is not enough { result.data[result.len - 1] %= 10; LongLongint new_result; delete [] new_result.data; new_result.len = result.len+1; new_result.data = new int[new_result.len]; for(int i = 0; i < new_result.len - 1; ++i) new_result.data[i] = result.data[i]; new_result.data[new_result.len - 1] = 1; return new_result; } } void LongLongint::display() { for(int i = len - 1; i >= 0; --i) cout << data[i]; } LongLongint operator+ (const LongLongint &num1, const LongLongint &num2) { LongLongint result; delete []result.data; //delete the initialize space bool islonger = (num1.len >= num2.len); result.len = islonger ? num1.len : num2.len; result.data = new int[result.len]; int shorter_len = (not islonger) ? num1.len : num2.len; for (int i = 0; i < shorter_len ; ++i) result.data[i] = num1.data[i] + num2.data[i]; for(int i = shorter_len; i < result.len; ++i) result.data[i] = islonger ? num1.data[i] : num2.data[i]; for (int i = 0; i < result.len - 1; ++i) //carry the number if(result.data[i] > 9) { result.data[i] %= 10; ++result.data[i+1]; } if(result.data[result.len - 1] < 10) //no need to carry return result; else //the length of the array is not enough { result.data[result.len - 1] %= 10; LongLongint new_result; delete [] new_result.data; new_result.len = result.len+1; new_result.data = new int[new_result.len]; for(int i = 0; i < new_result.len - 1; ++i) new_result.data[i] = result.data[i]; new_result.data[new_result.len - 1] = 1; return new_result; } } ostream &operator << (ostream &os, const LongLongint &num) { for (int i = num.len - 1; i >= 0; --i) os << num.data[i]; return os; }