STL generic programming Anar Manafov A Manafovgsi de

STL !!!generic programming!!! Anar Manafov (A. Manafov@gsi. de)

STL (Standard Template Library) or STL stands for Stepanov and Lee The Evolution STL is not a new library as compared to other libraries. Originally, the development of the STL was started by Alexander Stepanov at HP in 1979. Later, he was joined by David Musser and Meng Lee. In 1994, STL was included into ANSI and ISO C++. http: //www. stepanovpapers. com/ recommended link (Al Stevens Interviews Alex Stepanov, March 1995 issue of Dr. Dobb's Journal, ): http: //www. sgi. com/tech/stl/drdobbs-interview. html

STL Components Here is a list of elements of the STL. The first three of them are fundamental items. - Container (An object that holds other objects) - Algorithm (A function that acts on containers) - Iterator (A pointer-like object) - Allocator (This item manages memory allocation in a container) - Adaptor (Transforms one object into another) - Predicate (A function that returns a boolean value, true or false. ) - Function Object (A class that defines operator(). ) Recommended link: http: //www. sgi. com/tech/stl/ and http: //www. sgi. com/tech/stl_index. html

STL Components

containers, iterators, algorithms vector <T> sort list <T> find

containers, iterators, algorithms #include <vector> #include <algorithm> #include <iostream> using namespace std; int ia[10]={33, 17, 11, 88, 43, 99, 6, 9, 12, 7}; int main(){ vector<int> x(ia, ia+10); 33 17 11 88 43 99 6 9 12 7 sort(x. begin(), x. end()); end() begin() 6 7 9 11 12 17 33 43 88 99

// grab value to search for int s_value; cin >> s_value; // search for an element vector<int>: : iterator found; found=find(x. begin(), x. end(), s_value); if(found != x. end()) { cout << "search value found!n"; } else { cout << "search value not found!n"; } }

list instead of vector #include <list> #include <algorithm> #include <iostream> using namespace std; int ia[10]={33, 17, 11, 88, 43, 99, 6, 9, 12, 7}; int main(){ list<int> x(ia, ia+10); sort(x. begin(), x. end());

// grab value to search for int s_value; cin >> s_value; // search for an element list<int>: : iterator found; found=find(x. begin(), x. end(), s_value); if(found != x. end()) { cout << "search value found!n"; } else { cout << "search value not found!n"; } }

Algorithms with built-in arrays #include <algorithm> #include <iostream> using namespace std; int ia[10]={33, 17, 11, 88, 43, 99, 6, 9, 12, 7}; int main(){ int s_value; cout << "enter search value: "; cin >> s_value; int *found; found=find(&ia[0], &ia[10], s_value); if(found != ia+10). . .

Containers Sequence Containers Vector List Deque Stack Queue Adaptor Priority_queue Associative Containers Map Multimap Set Multiset Almost Containers Built-in arrays, strings, valarrays, bitsets

Containers

Container Vector: Deque: List: Set/Multiset: Map/Multimap:

string Type #include <iostream> #include <string> #include <algorithm> using namespace std; string s 1("Hello"); string s 2("World"); cout << s 1 + " " + s 2 + 'n'; string s 3(s 1 + " " + s 2); cout << '"'<< s 3 << "" has " << s 3. length() << " characters" << endl; replace(s 3. begin(), s 3. end(), 'W', 'w'); cout << s 3 << endl;

Constructors container() container(n) (not for ass. cont. ) container(n, x) (not for ass. cont. ) container(first, last) container(c) ~container()

Stack, Queue, List Operations push_back() pop_back() push_front() pop_front() insert(p, x) insert(p, n, x) insert(p, first, last) erase(p) erase(first, last) clear()

Algorithms • • • copy sort find fill partition insert, delete union, intersection accumulate. . .

Iterators • The glue that makes it possible to use generic algorithms and orthogonalize those algorithms from the data structures • An iterator i is a generalized means of traversing a data structure: – for an array, an array index or a pointer • Dereferencing an iterator, *i, is guaranteed to give the item, but an iterator does not obey all pointer operations

Iterators, Element Access begin() end() rbegin() rend() front() back() [] at() Points to first element Points to one-past-last element Points to first element of reverse seq. Points to one-past-last element of rev. seq. First element Last element Subscripting, unchecked access Subscripting, checked access

Iterator Operations

Iterators (continued) container<T>: : iterator first=c. begin(); container<T>: : iterator last=c. end(); [first, last) ++i; first == last; i != last; i + n; (long jump) *i = x; x = *i;

Nonmodifying Sequence Operations for_each() find_if() find_first_of() adjacent_find() count_if() mismatch() equal() search() find_end() search_n() list<Person*> all; . . . for_each(all. begin(), all. end(), Print(cout));

Function objects class b. Than{ public: b. Than(int x): test. Val(x) {} const int test. Val; bool operator()(int val){return val>test. Val; } }; list<int>: : iterator first. Big = find_if(a. List. begin(), a. List. end(), b. Than(12));

OO ? • STL is not OO, is OOP dead? • Not all problems are best solved in OOP fashion! • Many problems are best solved in an OOP manner. • Know as much as you can about as many styles of programming as you can, an use the style most appropriate to the problem.

#include <iostream> #include <map> #include <string> using namespace std; int main() { map<string, long, less<string> > directory; directory["Anar"] = 2128; directory["Victor"] = 1395; directory["Demo"] = 12344; string name; while (cin >> name) { if ( directory. find(name) != directory. end() ) cout << "The phone number for " << name << " is " << directory[name] << endl; else cout << "Sorry, no listing for " << name << endl; } }

#include <iostream> #include <map> #include <string> using namespace std; typedef map<string, long, less<string> > Directory_t; typedef Directory_t: : value_type Entry; int main() { Directory_t directory; // Will change the value of the key or insert if the key is exist already directory["Anar"] = 2128; // will insert or fail if the key is exist already directory. insert ( make_pair<string, long>("Victor", 1395) ); directory. insert( Entry("Demo", 12344) ); string name; while (cin >> name) { Directory_t: : iterator iter = directory. find(name); if ( iter != directory. end() ) cout << "The phone number for " << iter->first << " is " << (*iter). second << endl; else cout << "Sorry, no listing for " << name << endl; } }

Some real life examples small, but very handy! /*! fn void Trim. Right(std: : basic_string<_T> &_str, const std: : basic_string<_T> &_Val) brief Trims trailing characters from the string. param _Val - [in] The target characters to be trimmed. */ template<typename _T> void Trim. Right(std: : basic_string<_T> &_str, const std: : basic_string<_T> &_Val) { _str. resize( _str. find_last_not_of( _Val ) + 1 ); } /*! fn void Trim. Left(std: : basic_string<_T> &_str, const std: : basic_string<_T> &_Val) brief Trims leading characters from the string. param _Val - [in] The target characters to be trimmed. */ template<typename _T> void Trim. Left(std: : basic_string<_T> &_str, const std: : basic_string<_T> &_Val) { _str. erase( 0, _str. find_first_not_of( _Val ) ); }