好吧,我有1个用户定义的类型,名称为fraction
,它代表分子和分母的普通分数。这里是代码:C++ - 排序算法没有看到我的重载“<”运算符为用户定义的类型。
class Fraction
{
private:
int numerator;
int denominator;
public:
Fraction(int numer,int denom)
:numerator(numer),denominator(denom){}
int get_denom(){return denominator;}
int get_numer(){return numerator;}
};
正如你所看到的,它完全实现在头文件中。
所以我想要做的就是使用排序算法对分数向量进行排序。这里是重载“<”运营商的代码(注:它被放置在同一个文件中Fraction类,但外面的类):
bool operator<(Fraction& first,Fraction& second)
{
if(first.get_denom() == second.get_denom())
{
return first.get_numer()<second.get_numer()?true:false;
}
int first_num=first.get_denom();
int second_num=second.get_denom();
int lcm=(first_num*second_num)/gcd(first_num,second_num);
int first_new_numerator=(lcm/first_num)*first.get_numer();
int second_new_numerator=(lcm/second_num)*second.get_numer();
return first_new_numerator<second_new_numerator?true:false;
}
它所做的是检查,如果分母是相等的,如果他们再它测试分子的值。如果它们不相等,则使用最小公倍数和gcd来均衡它们。
当我要使用的排序算法在main(编译时错误)。这里是主要的代码真正的问题开始:
Fraction parse_fraction(string& input)
{
stringstream fraction_string(input);
int numer;
fraction_string>>numer;
char seperator;
fraction_string>>seperator;
int denom;
fraction_string>>denom;
return Fraction(numer,denom);
}
int main()
{
vector<Fraction> fractions;
string input;
while(cin>>input)
{
if(input=="|") break;
fractions.push_back(parse_fraction(input));
}
sort(fractions.begin(),fractions.end);
for(int i=0;i<fractions.size();i++)
{
cout<<fractions[i];
}
return 0;
}
错误,我得到的是(注:我已经正确重载“< <“运营商的部分,但不希望使杂波这里):
/usr/include/c++/4.6/bits/stl_algo.h||In function ‘_RandomAccessIterator std::__unguarded_partition(_RandomAccessIterator, _RandomAccessIterator, const _Tp&) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Fraction*, std::vector<Fraction> >, _Tp = Fraction]’:|
/usr/include/c++/4.6/bits/stl_algo.h:2253|70|instantiated from ‘_RandomAccessIterator std::__unguarded_partition_pivot(_RandomAccessIterator, _RandomAccessIterator) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Fraction*, std::vector<Fraction> >]’|
/usr/include/c++/4.6/bits/stl_algo.h:2284|54|instantiated from ‘void std::__introsort_loop(_RandomAccessIterator, _RandomAccessIterator, _Size) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Fraction*, std::vector<Fraction> >, _Size = long int]’|
/usr/include/c++/4.6/bits/stl_algo.h:5330|4|instantiated from ‘void std::sort(_RAIter, _RAIter) [with _RAIter = __gnu_cxx::__normal_iterator<Fraction*, std::vector<Fraction> >]’|
/home/vanio/Desktop/workspace/C++/Ordner/main.cpp:35|43|instantiated from here|
/usr/include/c++/4.6/bits/stl_algo.h|2212|error: no match for ‘operator<’ in ‘__first.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = Fraction*, _Container = std::vector<Fraction>, __gnu_cxx::__normal_iterator<_Iterator, _Container>::reference = Fraction&]() < __pivot’|
/usr/include/c++/4.6/bits/stl_algo.h|2212|note: candidates are:|
/usr/include/c++/4.6/bits/stl_pair.h|207|note: template<class _T1, class _T2> bool std::operator<(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)|
/usr/include/c++/4.6/bits/stl_iterator.h|291|note: template<class _Iterator> bool std::operator<(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&)|
/usr/include/c++/4.6/bits/stl_iterator.h|341|note: template<class _IteratorL, class _IteratorR> bool std::operator<(const std::reverse_iterator<_IteratorL>&, const std::reverse_iterator<_IteratorR>&)|
/usr/include/c++/4.6/bits/basic_string.h|2510|note: template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const std::basic_string<_CharT, _Traits, _Alloc>&, const std::basic_string<_CharT, _Traits, _Alloc>&)|
/usr/include/c++/4.6/bits/basic_string.h|2522|note: template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const std::basic_string<_CharT, _Traits, _Alloc>&, const _CharT*)|
/usr/include/c++/4.6/bits/basic_string.h|2534|note: template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const _CharT*, const std::basic_string<_CharT, _Traits, _Alloc>&)|
/usr/include/c++/4.6/bits/stl_vector.h|1290|note: template<class _Tp, class _Alloc> bool std::operator<(const std::vector<_Tp, _Alloc>&, const std::vector<_Tp, _Alloc>&)|
/home/vanio/Desktop/workspace/C++/Ordner/Fraction.h|39|note: bool operator<(Fraction&, Fraction&)|
/home/vanio/Desktop/workspace/C++/Ordner/Fraction.h|39|note: no known conversion for argument 2 from ‘const Fraction’ to ‘Fraction&’|
/usr/include/c++/4.6/bits/stl_algo.h|2215|error: no match for ‘operator<’ in ‘__pivot < __last.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = Fraction*, _Container = std::vector<Fraction>, __gnu_cxx::__normal_iterator<_Iterator, _Container>::reference = Fraction&]()’|
/usr/include/c++/4.6/bits/stl_algo.h|2215|note: candidates are:|
/usr/include/c++/4.6/bits/stl_pair.h|207|note: template<class _T1, class _T2> bool std::operator<(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)|
/usr/include/c++/4.6/bits/stl_iterator.h|291|note: template<class _Iterator> bool std::operator<(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&)|
/usr/include/c++/4.6/bits/stl_iterator.h|341|note: template<class _IteratorL, class _IteratorR> bool std::operator<(const std::reverse_iterator<_IteratorL>&, const std::reverse_iterator<_IteratorR>&)|
/usr/include/c++/4.6/bits/basic_string.h|2510|note: template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const std::basic_string<_CharT, _Traits, _Alloc>&, const std::basic_string<_CharT, _Traits, _Alloc>&)|
/usr/include/c++/4.6/bits/basic_string.h|2522|note: template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const std::basic_string<_CharT, _Traits, _Alloc>&, const _CharT*)|
/usr/include/c++/4.6/bits/basic_string.h|2534|note: template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const _CharT*, const std::basic_string<_CharT, _Traits, _Alloc>&)|
/usr/include/c++/4.6/bits/stl_vector.h|1290|note: template<class _Tp, class _Alloc> bool std::operator<(const std::vector<_Tp, _Alloc>&, const std::vector<_Tp, _Alloc>&)|
/home/vanio/Desktop/workspace/C++/Ordner/Fraction.h|39|note: bool operator<(Fraction&, Fraction&)|
/home/vanio/Desktop/workspace/C++/Ordner/Fraction.h|39|note: no known conversion for argument 1 from ‘const Fraction’ to ‘Fraction&’|
||=== Build finished: 22 errors, 0 warnings ===|
如果让操作员成为班级成员,会发生什么情况? 'bool operator <(Fraction&second)' – TheSteve 2012-07-31 00:19:02
您应该将'operator <'的参数定义为'const'引用。 – 2012-07-31 00:21:00
两种编码风格建议。 **第一:**而不是'return a?true:false'只是'return a'。 **第二:** gcd正在为这个问题(和缓慢)用大炮杀死苍蝇。只需乘以两个分母即可。你甚至可以跳过检查分母是否相等,这可能会花费更多的CPU周期。 – 2012-07-31 00:21:52