A recap of the STL and A recap of the STL and more containersmore containers

Plus an intro to string and file Plus an intro to string and file input and output!input and output!

Lecture 8Lecture 8

Standard template library (STL)Standard template library (STL) General purpose library of data structures General purpose library of data structures

and algorithmsand algorithms Everything in the STL is a templateEverything in the STL is a template Containers e.g. <map> <vector> <list>Containers e.g. <map> <vector> <list> Algorithms e.g. sort, find, for_each, searchAlgorithms e.g. sort, find, for_each, search IteratorsIterators

Generalization of pointersGeneralization of pointers Access data within containersAccess data within containers Reverse, Forward and randomReverse, Forward and random

Sequential containersSequential containers Containers:Containers:

std::vector<int> v (dynamic array)std::vector<int> v (dynamic array) std::list <int> l (doubly linked list)std::list <int> l (doubly linked list) std::deque<int> dq (double ended queue)std::deque<int> dq (double ended queue)

Adaptors:Adaptors: std::queue<int> qstd::queue<int> q std::stack<int> sstd::stack<int> s std::priority_queue<int> pq (A heap)std::priority_queue<int> pq (A heap)

Container adaptors are made specifically Container adaptors are made specifically to behave in a certain wayto behave in a certain way

stack – last in first outstack – last in first out queue –first in first outqueue –first in first out

Associative containersAssociative containers

Set – Unique keys, specific order, think of Set – Unique keys, specific order, think of it as a binary search treeit as a binary search tree std::set<int> first;std::set<int> first; std::set<int, comparison function> first; std::set<int, comparison function> first;

Map – Unique keys, specific order, key Map – Unique keys, specific order, key value pair, binary search tree value pair, binary search tree implementationimplementation Operator [] allows access to get value by keyOperator [] allows access to get value by key

Map<Type, Key>Map<Type, Key>

std::map<int, string> mymap;std::map<int, string> mymap;mymap[0]=“hello”;mymap[0]=“hello”;mymap[1]=“random”;mymap[1]=“random”;

mymap.insert<std::pair<int, string>(0, mymap.insert<std::pair<int, string>(0, “hello”));“hello”));

std::map newmap;std::map newmap;newmap.insert<mymap.begin(), mymap.find(1)>newmap.insert<mymap.begin(), mymap.find(1)>

Multi key containersMulti key containers

std::<multiset> msstd::<multiset> ms Same as a set but allows keys of the same Same as a set but allows keys of the same

value to existvalue to exist std::<multimap> mmstd::<multimap> mm

Same as a map but allows multiple keys of Same as a map but allows multiple keys of the same valuethe same value

StreamsStreams (part of the standard (part of the standard C++ library)C++ library)

<iostream> – input output stream objects<iostream> – input output stream objects ostream – output stream objectsostream – output stream objects istream – input stream objectsistream – input stream objects

istreamistream ifstream – input file streamifstream – input file stream istringstream – input string streamistringstream – input string stream

ostreamostream ofstream – output file streamofstream – output file stream ostringstream – output string streamostringstream – output string stream

<sstream><sstream> Provides both input and outputProvides both input and output << input data<< input data >> output data>> output data

std::stringstream ss;std::stringstream ss;ss << 5 << “hello”;ss << 5 << “hello”;int f;int f;string s;string s;ss >> f; //now has value 5ss >> f; //now has value 5ss >> s; //now has value “hello”ss >> s; //now has value “hello”

<fstream><fstream>

Similar to sstreamSimilar to sstream

ofstream myfile;ofstream myfile;myfile.open(“test.txt”); //open a filemyfile.open(“test.txt”); //open a filemyfile << “hello word\n”; //write into the filemyfile << “hello word\n”; //write into the filemyfile.close(); //close the filemyfile.close(); //close the file

ofstream myfile (“test.txt”);ofstream myfile (“test.txt”);

Reading from fileReading from file

ifstream myfile;ifstream myfile;myfile.open(“test.txt”); //open a filemyfile.open(“test.txt”); //open a filestring line;string line;while ( getline (myfile,line) ) while ( getline (myfile,line) )

{ { cout << line << '\n'; cout << line << '\n'; }} myfile.close(); myfile.close(); myfile.close(); //close the filemyfile.close(); //close the file