1. 1 STL Partea 2

2. D. Lucanu STL – Partea 2 2 Cuprins STL C++ containere standard algoritmi clasificare exemple: liste tablouri asociative agenda telefonica functori (obiecte functii)

3. D. Lucanu STL – Partea 2 3 STL :: algoritmi definitie (in STL): un set de template-uri care actioneaza asupra secventelor de elemente clasificare Nonmodifying algorithms Modifying algorithms Removing algorithms Mutating algorithms Sorting algorithms Sorted range algorithms Numeric algorithms

4. D. Lucanu STL – Partea 2 4 STL: algoritmi care nu modifica for_each() Performs an operation for each element count() Returns the number of elements count_if() Returns the number of elements that match a criterion min_element() Returns the element with the smallest value max_element() Returns the element with the largest value find() Searches for the first element with the passed value find_if() Searches for the first element that matches a criterion

5. D. Lucanu STL – Partea 2 5 STL: algoritmi care nu modifica search_n() Searches for the first n consecutive elements with certain properties search() Searches for the first occurrence of a subrange find_end() Searches for the last occurrence of a subrange find_first_of() Searches the first of several possible elements adjacent_find() Searches for two adjacent elements that are equal(by some criterion) equal() Returns whether two ranges are equal mismatch() Returns the first elements of two sequences that differ lexicographical_compare() Returns whether a range is lexicographically less than another range

6. D. Lucanu STL – Partea 2 6 STL: algoritmi care modifica for_each() Performs an operation for each element copy() Copies a range starting with the first element copy _backward() Copies a range starting with the last element transform() Modifies (and copies) elements; combines elements of two ranges merge() Merges two ranges swap_ranges() Swaps elements of two ranges fill() Replaces each element with a given value fill_n() Replaces n elements with a given value

7. D. Lucanu STL – Partea 2 7 STL: algoritmi care elimina remove() Removes elements with a given value remove_if() Removes elements that match a given criterion remove_copy() Copies elements that do not match a given value remove_copy_if() Copies elements that do not match a given criterion unique() Removes adjacent duplicates (elements that are equal to their predecessor) unique_copy() Copies elements while removing adjacent duplicates

8. D. Lucanu STL – Partea 2 8 STL: algoritmi care schimba ordinea reverse() Reverses the order of the elements reverse_copy() Copies the elements while reversing their order rotate() Rotates the order of the elements rotate_copy() Copies the elements while rotating their order next_permutation() Permutates the order of the elements prev_permutation() Permutates the order of the elements

9. D. Lucanu STL – Partea 2 9 STL: algoritmi care schimba ordinea random_shuffle() Brings the elements into a random order partition() Changes the order of the elements so that elements that match a criterion are at the front stable_partition() Same as partition() but preserves the relative order of matching and nonmatching elements

10. D. Lucanu STL – Partea 2 10 STL: algoritmi care modifica generate() Replaces each element with the result of an operation generate_n() Replaces n elements with the result of an operation replace() Replaces elements that have a special value with another value replace_if() Replaces elements that match a criterion with another value replace_copy() Replaces elements that have a special value while copying the whole range replace_copy_if() Replaces elements that match a criterion while copying the whole range

11. D. Lucanu STL – Partea 2 11 STL: algoritmi de sortare sort() Sorts all elements stable_sort() Sorts while preserving order of equal elements partial_sort() Sorts until the first n elements are correct partial_sort_copy() Copies elements in sorted order nth_element() Sorts according to the nth position partition() Changes the order of the elements so that elements that match a criterion are at the front

12. D. Lucanu STL – Partea 2 12 STL: algoritmi de sortare stable_partition() Same as partition() but preserves the relative order of matching and nonmatching elements make_heap() Converts a range into a heap push_heap() Adds an element to a heap pop_heap() Removes an element from a heap sort_heap() Sorts the heap (it is no longer a heap after the call)

13. D. Lucanu STL – Partea 2 13 STL: algoritmi pe intervale sortate binary_search() Returns whether the range contains an element includes() Returns whether each element of a range is also an element of another range lower_bound() Finds the first element greater than or equal to a given value upper _bound() Finds the first element greater than a given value equal_range() Returns the range of elements equal to a given value merge() Merges the elements of two ranges set_union() Processes the sorted union of two ranges

14. D. Lucanu STL – Partea 2 14 STL: algoritmi de sortare pe intervale set_intersection() Processes the sorted intersection of two ranges set_difference() Processes a sorted range that contains all elements of a range that are not part of another set_symmetric_difference() Processes a sorted range that contains all elements that are in exactly one of two ranges inplace_merge() Merges two consecutive sorted ranges

15. D. Lucanu STL – Partea 2 15 STL: algoritmi numerici accumulate() Combines all element values (processes sum, product, and so forth) inner_product() Combines all elements of two ranges adjacent_difference() Combines each element with its predecessor partial_sum() Combines each element with all of its predecessors

16. D. Lucanu STL – Partea 2 16 STL :: algoritmi::liste header #include declarare lista list amici; afisare componentelor listei void print_string(string s) { cout << s << endl; } //... p = amici.begin(); q = amici.end(); for_each(p, q, print_string);

17. D. Lucanu STL – Partea 2 17 STL :: algoritmi::liste numara Popestii int n = count(p, q, "Popescu"); cauta dupa criteriu defineste criteriu (rau = nu incepe cu litera) int bad(const string& s) { return !isalpha(s[0]); } insereaza un element rau amici.insert(q, "12cai"); gaseste primul element rau (care nu incepe cu litera) p = find_if( amici.begin(), amici.end(), bad );

18. D. Lucanu STL – Partea 2 18 STL :: inseratori fie functia: void f(list & li) { fill_n(li.begin(), 100, 77); } f() atribuie 77 elementelor li[0],..., li[99] dar daca sunt mai putin de 100 de elemente?

19. D. Lucanu STL – Partea 2 19 STL :: inseratori in exista trei clase parametrizate create pentru a rezolva astfel de probleme template back_insert_iterator back_inserter(Cont& c); template front_insert_iterator front_inserter(Cont& c); template insert_iterator inserter(Cont& c, Out p);

20. D. Lucanu STL – Partea 2 20 STL :: inseratori adaugarea de elemente la sfarsit: void g(list & li) { fill_n(back_inserter(li), 100, 77); } // se vor adauga 100 copii ale lui 77 la sf. inserare mai simpla insert_inserator > ii(li, p);... *ii = 55; // este echivalent cu li.insert(p, 55)

21. D. Lucanu STL – Partea 2 21 STL :: algoritmi::liste (cont) // creeaza o copie numai cu unicate list copie; unique_copy(amici.begin(), amici.end(), \ back_inserter(copie)); amici = copie; inserarea unei liste in alta lista list temp; temp.push_back("Albu"); //... q = find(amici.begin(), amici.end(), "Popescu"); copy(temp.begin(), temp.end(), \ inserter(amici, q));

22. D. Lucanu STL – Partea 2 22 STL :: algoritmi::map clasa Persoana class Persoana { //... friend bool operator<(const Persoana& lhs, \ const Persoana& rhs); //... }; clasa Info (despre persoana) class Info { //... private: string adr; string nr; };

23. D. Lucanu STL – Partea 2 23 STL :: algoritmi::map declarare agenda telefonica multimap agTel; afisare agenda afisare intrare void print_intrare(pair p) { cout << p.first.getNume() //...; } apelare alg. for_each() p = agTel.begin(); q = agTel.end(); for_each(p, q, print_intrare);

24. D. Lucanu STL – Partea 2 24 STL :: algoritmi::map numara Popestii declarare criteriu bool eqPopescu(pair p) { return p.first.getNume() == "Popescu"; } apelare algoritm count_if() p = agTel.begin(); q = agTel.end(); cout << count_if(p, q, eqPopescu);

25. D. Lucanu STL – Partea 2 25 STL::ex:: agenda telefonica cheia va fi un nume typedef std::string Nume; clasa AgTel deriveaza din multimap<> class AgTel : public std::multimap { public: AgTel (); AgTel(char* numeFisier); void adIntrare(); void afiseazaTot(); void incarca(char* numeFisier); void salveaza(char* numeFisier); //... };

26. D. Lucanu STL – Partea 2 26 STL::ex:: agenda telefonica memorarea agendei in fisier fiecare intrare este memorata pe 3 linii: fisierul va avea 3*nr_intrari linii

27. D. Lucanu STL – Partea 2 27 STL::ex:: agenda telefonica void AgTel::incarca(char* numeFisier) { //... bool ok = std::getline(inp, nume); while(ok) { ok = std::getline(inp, adr); //... if (ok) this->insert(end(), std::make_pair(nume, Info(adr, nr))); ok = std::getline(inp, nume); } inp.close(); }

28. D. Lucanu STL – Partea 2 28 STL::ex:: agenda telefonica void AgTel::adIntrare() { //... std::cout << "Nume: "; std::cin >> s; Nume nume(s); //... this->insert(end(), \ std::make_pair(nume, info)); }

29. D. Lucanu STL – Partea 2 29 STL::ex:: agenda telefonica void AgTel::salveaza(char *numeFisier) { std::ofstream out(numeFisier); AgTel::iterator i; for (i=this->begin(); i!=this->end(); ++i) { out first << std::endl; out second.getAdr() << std::endl; out second.getNr() << std::endl; } out.close(); }

30. D. Lucanu STL – Partea 2 30 STL::ex:: agenda telefonica:: demo int main() { int optiune; AgTel agTel; do { std::cout << "1. Initializeaza...”; //... std::cout << "0. Terminare.\n"; std::cin >> optiune;

31. D. Lucanu STL – Partea 2 31 STL::ex:: agenda telefonica:: demo switch (optiune) { case 1: agTel.clear(); break; case 4: agTel.salveaza("test.at"); break; //... } } while (optiune != 0); return 0; }

32. D. Lucanu STL – Partea 2 32 Obiecte de tip functie A function object (or functor), is an object that has operator () defined so that in the following example FunctionObjectType fo;... fo(...); the expression fo() is a call of operator () for the function object fo instead of a call of the function fo()

33. D. Lucanu STL – Partea 2 33 Obiecte de tip functie Instead of writing all the function statements inside the function body, void fo() { statements } you write them inside the body of operator () of the function object class: class FunctionObjectType { public: void operator()() { statements } };

34. D. Lucanu STL – Partea 2 34 Obiecte de tip functie: avantaje A function object might be smarter because it may have a state. In fact, you can have two instances of the same function, represented by a function object, which may have different states at the same time. This is not possible for ordinary functions. Each function object has its own type. Thus, you can pass the type of a function object to a template to specify a certain behavior, and you have the advantage that container types with different function objects differ. A function object is usually faster than a function pointer.

35. D. Lucanu STL – Partea 2 35 Obiecte de tip functie: sortare class Person { public: string firstname() const; string lastname() const; //... }; class PersonSortCriterion { public: bool operator() (const Person& p1, const Person& p2) const { return p1.lastname() < p2.1astname() || ((p2.1astname() == p1.lastname()) && p1.firstname() < p2.firstname()); } };

36. D. Lucanu STL – Partea 2 36 Obiecte de tip functie: sortare int main() { //declare set type with special sorting criterion typedef set PersonSet; //create such a collection PersonSet coll;... //do something with the elements PersonSet::iterator pos; for (pos = coll.begin(); pos != coll.end(); ++pos) {... }... }

37. D. Lucanu STL – Partea 2 37 Obiecte de tip functie cu stare interna In this example, a function object is used that generates a sequence of integral values. Each time operator () is called, it returns its actual value and increments it. You can pass the start value as a constructor argument. class IntSequence { private: int value; public: //constructor IntSequence (int initialValue) : value(initialValue) { } //''function call'' int operator() () { return value++; } };

38. D. Lucanu STL – Partea 2 38 Obiecte de tip functie cu stare interna utilizarea a unei functii cu generate_n() list coll; //insert values from 1 to 9 generate_n (back_inserter(coll), //start 9, //number of elements IntSequence (1)); //generates //values coll’s contents: 1; 2; 3; 4; 5; 6; 7; 8; 9;

39. D. Lucanu STL – Partea 2 39 Obiecte de tip functie cu stare interna utilizarea a unei functii cu generate_n() generate (++coll.begin(), //start --coll.end(), //end IntSequence (42)); //generates // values coll’s contents: 1; 42; 43; 44; 45; 46; 47; 48; 9; demo

40. D. Lucanu STL – Partea 2 40 Obiecte de tip functie cu stare interna Function objects are passed by value rather than by reference. IntSequence seq(1); //integral sequence //starting with value 1 //insert sequence beginning with 1 generate_n (back_inserter(coll), 9, seq); //insert sequence beginning with 1 again generate_n (back_inserter(coll), 9, seq); demo

41. D. Lucanu STL – Partea 2 41 Obiecte de tip functie cu stare interna However, access to the final state might be necessary, so the question is how to get a "result" from an algorithm. There are two ways to get a "result" or "feedback" from using function objects with algorithms: You can pass the function objects by reference. You can use the return value of the for_each() algorithm. create a function object: IntSequence seq(1);

42. D. Lucanu STL – Partea 2 42 Obiecte de tip functie cu stare interna to pass seq by reference in generate_n(), the template arguments are qualified explicitly: generate_n >, int, IntSequence&> (back_inserter(coll), //start 4, //number of elements seq); //generates values demo

43. D. Lucanu STL – Partea 2 43 Obiecte de tip functie predefinite ExpressionEffect negate () - param plus () param1 + param2 minus () param 1 - param2 multiplies () param1 * param2 divides () param1 / param2 modulus () param1 % param2 equal_to () param1 == param2 not_equal_to () param1 ! = param2

44. D. Lucanu STL – Partea 2 44 Obiecte de tip functie predefinite ExpressionEffect less () param1 < param2 greater () param1 > param2 less_equal () param1 <= param2 greater_equal () param1 >= param2 logical_not ()! param logical_and () param1 && param2 logical_or () param1 | | param2