Summary - STL containers

Combine vector, map and set to write a phone book.

Summary - STL containers

In this group you learned five core STL containers. std::vector is a dynamic array, std::list a doubly linked list, std::map an ordered key-value store, std::unordered_map a hash table, std::set a unique sorted set.

In the final task you'll combine vector and set: create a vector with duplicate elements, then build a set from it. The set ignores duplicates, so its size gives the unique count. This is a common container-composition pattern.

Exercise Mini task: combine vector and set

Create std::vector<int> v;; add 1, 2, 2, 3 with push_back. Build std::set<int> s(v.begin(), v.end());. Print s.size().

Show example solution

#include <iostream>
#include <vector>
#include <set>

int main() {
    std::vector<int> v;
    v.push_back(1);
    v.push_back(2);
    v.push_back(2);
    v.push_back(3);
    std::set<int> s(v.begin(), v.end());
    std::cout << s.size() << std::endl;
    return 0;
}

Test yourself

Which container for fast O(1) access when order doesn't matter?
```
// anahtar-değer, sıralama önemli değil
```
- std::map
- std::set
- std::list
- std::unordered_map
Show answer

std::unordered_map — unordered_map offers average O(1) access; no ordering.
Match container to property

std::vector

Dynamic array
std::list

Doubly linked list
std::map

Ordered key-value
std::set

Unique sorted

Key-value container

std::____<std::string, int> m;

Show answer

std::map<std::string, int> m;

Next lesson: What are iterators?

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