泛型算法系列36:lexicographical_compare()

#include <algorithm> #include <list> #include <string> #include <assert.h> #include <iostream>using namespace std;class size_compare{ public: bool operator()( const string &a, const string &b ){ bool ret = (a.length() < b.length());return ret; } };/************************************************************************//* */template<class _InIt1, class _InIt2> inlinebool __CLRCALL_OR_CDECL my_Lexicographical_compare(_InIt1 _First1, _InIt1 _Last1, _InIt2 _First2, _InIt2 _Last2){// order [_First1, _Last1) vs. [First2, Last2)_DEBUG_RANGE(_First1, _Last1);_DEBUG_RANGE(_First2, _Last2);for (; _First1 != _Last1 && _First2 != _Last2; ++_First1, ++_First2){if (_DEBUG_LT(*_First1, *_First2))return (true);else if (*_First2 < *_First1)return (false);}return (_First1 == _Last1 && _First2 != _Last2);}template<class _InIt1, class _InIt2, class _Pr> inlinebool __CLRCALL_OR_CDECL my_Lexicographical_compare(_InIt1 _First1, _InIt1 _Last1,_InIt2 _First2, _InIt2 _Last2, _Pr _Pred){// order [_First1, _Last1) vs. [First2, Last2) using _Pred_DEBUG_RANGE(_First1, _Last1);_DEBUG_RANGE(_First2, _Last2);_DEBUG_POINTER(_Pred);for (; _First1 != _Last1 && _First2 != _Last2; ++_First1, ++_First2){if (_DEBUG_LT_PRED(_Pred, *_First1, *_First2))return (true);else if (_Pred(*_First2, *_First1))return (false);}return (_First1 == _Last1 && _First2 != _Last2);}/************************************************************************/int main() { string arr1[] = { "Piglet", "Pooh", "Tigger" }; string arr2[] = { "Piglet", "Pooch", "Eeyore" }; bool res;// evaluates to false at second element // Pooch is less than Pooh // would also evaluate false at third element res = my_Lexicographical_compare( arr1, arr1 + 3, arr2, arr2 + 3 ); assert( res == false ); // evaluates to true: each element of ilist2 // has a length less than or equal to the // associated ilist1 element list< string > ilist1( arr1, arr1 + 3 ); list< string > ilist2( arr2, arr2 + 3 ); res = my_Lexicographical_compare(ilist1.begin(), ilist1.end(), ilist2.begin(), ilist2.end(), size_compare() ); assert( res == true ); cout << "ok: lexicographical_compare succeeded!/n";return 0;}

 

//重载1，如果[first1, last1)按字典序列小于[first2, last2)，返回true，否则返回false。

//重载2，功能同重载1，增加了比较函数comp，即大小关系由comp函数确定。