Overloaded the operator for its class. In separate expressions when comparing errors there is no

cout << (StringLocation("123", 123) < StringLocation("123", 124)); // Вывод: 1

But when added to set

 map<string, set<StringLocation> > A; A["123"].insert(StringLocation("123", 213));

An error occurs:

no match for 'operator <' (operand types are 'const StringLocation' and 'const StringLocation')

How to designate this comparison operator to be seen by set ?

Code:

 #include <iostream> #include <map> #include <set> using namespace std; class StringLocation { private: std::string FileName; // Имя файла int lineOfLocation; // Номер строки public: StringLocation(std::string FileName_, int lineOfLocation_) { this->FileName = FileName_; this->lineOfLocation = lineOfLocation_; } std::string getFileName () { return this->FileName; } int getLineOfLocation () { return this->lineOfLocation; } /* * Перегрузка оператора сравнения */ bool operator < (const StringLocation& my_StringLocation) { if(this->FileName == my_StringLocation.FileName) return this->lineOfLocation < my_StringLocation.lineOfLocation; return this->FileName < my_StringLocation.FileName; } /* * Перегрузка ввода/вывода * * Выполняется только в том случае, если в основном файле * подключена библиотека <iostream> * * _GLIBCXX_IOSTREAM в MinGW * _IOSTREAM_ в MSCVS */ #if defined(_GLIBCXX_IOSTREAM) || defined(_IOSTREAM_) friend std::ostream& operator << (std::ostream &out, const StringLocation& my_StringLocation) { out << "Line " << my_StringLocation.lineOfLocation << ": " << my_StringLocation.FileName; return out; } #endif }; int main() { map<string, set<StringLocation> > A; A["123"].insert(StringLocation("123", 213)); }

UPD :

What if I need to write an operator! = For iterators?

 // Такая проверка не работает :C bool operator != (const StringLocation& my_StringLocation) const { return this->FileName != my_StringLocation.FileName && this->lineOfLocation != my_StringLocation.lineOfLocation; } std::set<StringLocation> get_info_about_word (std::string word) { auto it = this->invertedIndex[word]; if(it != this->invertedIndex.end()) // Сравнение! return it; }

    1 answer 1

    Make it constant:

     bool operator < (const StringLocation& my_StringLocation) const

    And it turns out that your comparison operator is trying to change the object being compared :) And the set "can't catch on etto" (c) :)

    • Problem solved - Andrey Varfolomeev
    • Can you see the addition to the question? - Andrey Varfolomeev
    • invertedIndex is what? You have no such thing in class. - Harry
    • invertedIndex is a field of another class. this-> invertedIndex returns map <string, set <StringLocation>> - Andrey Varfolomeev
    • error: no match for 'operator! =' (operand types are 'std :: set <StringLocation>' and 'std :: map <std :: __ cxx11 :: basic_string <char>, std :: set <StringLocation>>: : iterator {aka std :: _ Rb_tree_iterator <std :: pair <const std :: __ cxx11 :: basic_string <char>, std :: set <StringLocation>>>} ') | - Andrey Varfolomeev