[問題] 請問 copy+back_inserter 還有哪些用法？

看板C_and_CPP (C/C++)作者chrisdar (克里斯)時間16年前 (2009/05/10 00:01)推噓1(1推 0噓 3→)

留言4則, 3人參與討論串1/1

最近突發奇想，想把clase當成Container來用，以下是一個範例： http://src.wtgstudio.com/?dVl32d #include <iostream> #include <vector> #include <algorithm> #include <cmath> using namespace std; template <typename T> class MyStatistics { private: T m_Amount, m_Summation, m_Summation4Square; public: typedef MyStatistics<T> this_type; explicit inline MyStatistics(void): m_Amount(T()), m_Summation(T()), m_Summation4Square(T()) {} virtual inline ~MyStatistics(void) {} public: /* copy & back_inserter Requirement */ typedef T& reference; typedef const T& const_reference; inline this_type& push_back(const_reference e) { return AddElement(e); } public: /* for_each Requirement */ inline MyStatistics(const this_type& d): m_Amount(d.m_Amount), m_Summation(d.m_Summation), m_Summation4Square(d.m_Summation4Square) {} inline this_type& operator=(const this_type& d) { if (this != &d) { m_Amount = d.m_Amount; m_Summation = d.m_Summation; m_Summation4Square = d.m_Summation4Square; } return *this; } inline this_type& operator()(const T& e) { return AddElement(e); } public: inline this_type& AddElement(const T& e = T()) { m_Amount += 1; m_Summation += e; m_Summation4Square += e * e; return *this; } inline this_type& Clear(void) { m_Amount = T(); m_Summation = T(); m_Summation4Square = T(); return *this; } inline const T& GetNum(void) const { return m_Amount; } inline const T& GetSum(void) const { return m_Summation; } inline const double CalAverage(void) const { return m_Summation / double(m_Amount); } inline const double CalStandardDeviation(void) const { return sqrt(m_Summation4Square / double(m_Amount) - CalAverage()*CalAverage()); } }; template <typename T> inline ostream& operator <<(ostream& os, const MyStatistics<T>& d) { return os << "Summation/Amount: " << d.GetSum() << "/ " << d.GetNum() << "\n" << "Average,Standard Deviation: " << d.CalAverage() << ", " << d.CalStandardDeviation() << "\n" ; } int main(int argc, char* argv[]) { int ia[] = {4, 5, 5, 6, 3, 3, 4, 5, 3, 4, 2, 3, 6, 4, 5, 5, 23, 5, 5, 3, 6, 7, 3, 7}; typedef vector<int> myIntArray_type; myIntArray_type myInstWidth_c(ia, ia + sizeof(ia) / sizeof(ia[0])); MyStatistics<int> a; copy(myInstWidth_c.begin(), myInstWidth_c.end(), back_inserter(a)); cout << a << endl; a = for_each(myInstWidth_c.begin(), myInstWidth_c.end(), MyStatistics<int>()); cout << a << endl; system("PAUSE"); return 0; } 不知道這樣使用back_inserter是不是太邪魔歪道 >_< -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 123.195.88.23 ※ 編輯: chrisdar 來自: 123.195.88.23 (05/10 00:03)