AGENDA

• C++ data types
• Introduction to the STL
• std::vector
• std::map
• std::set
• Practical examples and exercises

Why the STL?

• The Standard Template Library (STL) provides ready-to-use data structures and algorithms.
• Saves development time, reduces bugs.
• Highly optimized and well-tested.
• Used everywhere in professional C++.

Basic Data Types

• Primitive: int, double, char, bool
• Derived: array, pointer, struct, class
• User-defined: your own types
• STL containers build on these to store data efficiently

std::vector

• Dynamic array that grows automatically
• Access elements with [] or .at()

#include <vector>
#include <iostream>
using namespace std;

int main() {
    vector<int> values = {1, 2, 3};
    values.push_back(4);

    for (int v : values)
        cout << v << " ";
}

Output:

1 2 3 4

std::vector – Common Operations

v.size();         // number of elements
v.empty();        // check if empty
v.clear();        // remove all elements
v.front();        // first element
v.back();         // last element
v.pop_back();     // remove last

std::map

• Associates keys with values, sorted by keys automatically

#include <map>
#include <iostream>
using namespace std;

int main() {
    map<string, int> scores;
    scores["Anna"] = 95;
    scores["Bob"] = 87;
    scores["Clara"] = 91;

    for (auto& [name, score] : scores)
        cout << name << ": " << score << endl;
}

Output:

Anna: 95
Bob: 87
Clara: 91

std::set

• Stores unique elements only, automatically sorted

#include <set>
#include <iostream>
using namespace std;

int main() {
    set<int> ids = {5, 3, 1, 3};
    ids.insert(2);
    for (int id : ids)
        cout << id << " ";
}

Output:

1 2 3 5

Example: Word Counter

src/main.cpp

#include <iostream>
#include <map>
#include <string>
#include <sstream>
using namespace std;

int main() {
    string text = "this is a test this is only a test";
    map<string, int> counter;
    string word;
    istringstream iss(text);
    while (iss >> word)
        counter[word]++;

    for (auto& [w, c] : counter)
        cout << w << " -> " << c << endl;
}

Example: Word Counter

Expected Output

a -> 2
is -> 2
only -> 1
test -> 2
this -> 2

Survival Package (STL Containers)

• vector: dynamic list of elements
• map: key-value store (sorted)
• set: unique sorted elements
• Use range-based for loops to iterate
• Always #include <container>

Wrap-Up

• Learned STL basics
• Practiced vectors, maps, and sets
• Built a simple word counter