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Advanced 20 min readModule: Module 9: Standard Template Library (STL) Containers & Algorithms

STL Containers (vector, unordered_map) & Algorithms

Master standard contiguous vectors, hash maps (unordered_map), and standard algorithms (std::sort, std::find).

What You Will Learn in This Lesson

  • Contiguous memory layout of std::vector for CPU cache efficiency
  • Hash-based lookups with std::unordered_map
  • Standard algorithms from <algorithm> using lambda predicates

Introduction & Core Concept

The Standard Template Library (STL) is a powerful set of C++ template classes to provide general-purpose classes and functions with templates that implement many popular algorithms and data structures.
WHY DOES THIS MATTER IN THE REAL WORLD?

std::vector stores elements contiguously in memory, making iteration drastically faster than pointer-chasing linked lists due to CPU cache locality.

Vector Sorting with Custom Lambda

cpp
cpp
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#include <iostream>
#include <vector>
#include <algorithm>
 
int main() {
    std::vector<int> data = {50, 10, 40, 20, 30};
    std::sort(data.begin(), data.end());
    std::cout << "Sorted STL Vector: ";
    for (int x : data) std::cout << x << " ";
    std::cout << std::endl;
    return 0;
}

Line-by-Line Technical Breakdown

1Use reserve() on std::vector to pre-allocate memory and avoid dynamic reallocation copies.

Try It Yourself (Interactive Editor)

Modify the code in real-time and click Run to test live browser output and console logs.

Intelligent Code Runner & Live Sandbox[CPP]
CPP SOURCE EDITOR
Interactive Live Code

Industry Best Practices & Professional Standards

  • Always default to std::vector unless you have a proven profiling need for another container.

Lesson Summary & Core Takeaways

  • The STL provides battle-tested, high-performance algorithms and containers.