STL Containers, Iterators, and Algorithms in Practice

Vector, Map, and Set

#include <vector>
#include <map>
#include <set>

std::vector<int> numbers = {1, 2, 3, 4};
std::map<std::string, int> ages;
ages["Alice"] = 25;
std::set<int> uniqueValues = {3, 1, 2};

These standard containers solve many everyday programming problems and are usually safer and more efficient than hand-written alternatives for common use cases.

Iterators

for (auto it = numbers.begin(); it != numbers.end(); ++it) {
    std::cout << *it << '\n';
}

Iterators generalize traversal across different container types. They are a key glue concept in the STL design.

Algorithms

#include <algorithm>

std::sort(numbers.begin(), numbers.end());
auto found = std::find(numbers.begin(), numbers.end(), 3);

Standard algorithms often replace manual loops with clearer, more reusable code. Students should learn to look for library algorithms before writing everything from scratch.

Range-Based Loops and Modern Style

for (const auto &value : numbers) {
    std::cout << value << '\n';
}

Choosing the Right Container

• Use std::vector for contiguous dynamic arrays and most general sequence work.
• Use std::map or std::unordered_map for key-value lookup.
• Use std::set or std::unordered_set for uniqueness tracking.

Real-World Usage Snapshot

Production C++ code relies heavily on STL containers and algorithms. Strong library fluency often produces safer and faster code than overusing raw arrays, manual loops, and custom containers where they are not needed.