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STL

C++ STL Lessons

Master the C++ Standard Template Library — containers, iterators, algorithms, allocators, utilities, adapters and ranges.

Course outline

Tracks and lessons

Track 01beginner

Module 1: STL Core Ideas

Master the C++ Standard Template Library through containers, iterators, algorithms, allocators, utilities, adapters, ranges.

01What the STL Is and Why It MattersSTL in Context The Standard Template Library is the most reusable part of modern C++. It gives you generic. Instead of writing a new loop for every data structure. Containers store data Iterators provide a common way to traverse databeginner

STL in Context The Standard Template Library is the most reusable part of modern C++. It gives you generic. Instead of writing a new loop for every data structure. Containers store data Iterators provide a common way to traverse data

Example
// STL mental model
const parts = ["containers", "iterators", "algorithms", "adapters", "utilities"];
parts.forEach((part, i) => console.log((i + 1) + ". " + part));
console.log("STL goal: generic code that works across many data structures");
Quiz

The STL is best described as:

Algorithms in the STL usually operate on:

One major benefit of the STL is:

02Sequence Containers: vector, deque, list, array, stringSequence Container Roles Good STL usage is not memorizing everything. It is choosing the right container for access patterns. std::vector for contiguous dynamic arrays and the best general-purpose. std::deque for efficient push/pop at both endsbeginner

Sequence Container Roles Good STL usage is not memorizing everything. It is choosing the right container for access patterns. std::vector for contiguous dynamic arrays and the best general-purpose. std::deque for efficient push/pop at both ends

Example
// Container trade-offs
const recommendations = {
  vector: "best default",
  deque: "double-ended queue",
  list: "linked list with stable nodes",
  array: "fixed size",
  string: "text container"
};
Object.entries(recommendations).forEach(([name, use]) => console.log(name + ": " + use));
Quiz

The best default dynamic container in most C++ code is:

std::array differs from std::vector because it is:

Container choice should depend on:

03Iterators, Range Semantics, and Generic TraversalIterators Connect Everything Iterators let algorithms work with many containers through a shared interface. This is why you can. STL algorithms commonly use [begin, end). The start is included. Input and output iterators Forward iteratorsbeginner

Iterators Connect Everything Iterators let algorithms work with many containers through a shared interface. This is why you can. STL algorithms commonly use [begin, end). The start is included. Input and output iterators Forward iterators

Example
// Iterator range idea
const values = [10, 20, 30, 40];
const begin = 0;
const end = values.length;
for (let i = begin; i < end; i += 1) console.log(values[i]);
console.log("Range is [begin, end)");
Quiz

Iterators are useful because they:

The STL commonly uses which range convention?

A random-access iterator supports:

Track 02beginner

Module 2: Algorithms and Utilities

Master the C++ Standard Template Library through containers, iterators, algorithms, allocators, utilities, adapters, ranges.

01Algorithms: sort, find, transform, remove, accumulateThink in Operations, Not Loops STL algorithms encode common intentions clearly: searching, sorting, filtering, partitioning, copying, and reducing values. This often. Searching: find, binary_search Ordering: sort, stable_sortbeginner

Think in Operations, Not Loops STL algorithms encode common intentions clearly: searching, sorting, filtering, partitioning, copying, and reducing values. This often. Searching: find, binary_search Ordering: sort, stable_sort

Example
// Algorithm style thinking
const data = [5, 2, 9, 2, 7];
console.log("sort ->", [...data].sort((a, b) => a - b).join(", "));
console.log("find 9 ->", data.indexOf(9));
console.log("transform x2 ->", data.map(x => x * 2).join(", "));
console.log("accumulate sum ->", data.reduce((s, x) => s + x, 0));
Quiz

One advantage of STL algorithms is that they:

remove_if is commonly used for:

accumulate is used to:

02Lambdas, Comparators, Predicates, and Function ObjectsCustomize Behavior Algorithms become truly powerful when you can inject behavior. Lambdas and function objects let you define. Prefer short lambdas for local logic and named function objects. Sorting by a custom field Filtering values by conditionintermediate

Customize Behavior Algorithms become truly powerful when you can inject behavior. Lambdas and function objects let you define. Prefer short lambdas for local logic and named function objects. Sorting by a custom field Filtering values by condition

Example
// Custom comparator example
const users = [
  { name:"Mia", score:91 },
  { name:"Leo", score:77 },
  { name:"Ana", score:95 }
];
users.sort((a, b) => b.score - a.score);
users.forEach(u => console.log(u.name + ": " + u.score));
Quiz

Lambdas are especially useful for:

A comparator is often used with:

A predicate typically returns:

03Associative and Unordered Containers: map, set, unordered_mapKey-Based Access Ordered containers keep keys sorted and support range operations. Unordered containers optimize for average-case lookup speed. std::map stores ordered key-value pairs std::set stores unique ordered keysintermediate

Key-Based Access Ordered containers keep keys sorted and support range operations. Unordered containers optimize for average-case lookup speed. std::map stores ordered key-value pairs std::set stores unique ordered keys

Example
// Key-value lookup patterns
const orderedUse = "sorted keys and range queries";
const hashedUse = "fast average lookup";
console.log("map -> " + orderedUse);
console.log("unordered_map -> " + hashedUse);
console.log("set -> unique ordered values");
Quiz

std::unordered_map is generally chosen for:

std::map keeps keys:

A set is useful when you need:

Track 03intermediate

Module 3: Production STL

Master the C++ Standard Template Library through containers, iterators, algorithms, allocators, utilities, adapters, ranges.

01Adapters, priority_queue, stack, queue, and Heap ThinkingContainer Adapters Adapters expose a specialized interface built on top of another container. Use adapters when you want a stronger API that communicates. std::stack for LIFO access std::queue for FIFO processingintermediate

Container Adapters Adapters expose a specialized interface built on top of another container. Use adapters when you want a stronger API that communicates. std::stack for LIFO access std::queue for FIFO processing

Example
// Adapter use cases
console.log("stack -> undo history");
console.log("queue -> job pipeline");
console.log("priority_queue -> scheduler or pathfinding frontier");
Quiz

A priority_queue returns:

A stack follows:

Adapters are helpful because they:

02Ranges, Views, and Modern STL StyleModern C++ Style C++20 ranges bring a more composable style to the STL. Instead of materializing intermediate containers everywhere. Classic STL already encourages generic thinking. Ranges extend that idea. They can avoid unnecessary copies They keepadvanced

Modern C++ Style C++20 ranges bring a more composable style to the STL. Instead of materializing intermediate containers everywhere. Classic STL already encourages generic thinking. Ranges extend that idea. They can avoid unnecessary copies They keep

Example
// Range pipeline mindset
const values = [1, 2, 3, 4, 5, 6];
const result = values.filter(x => x % 2 === 0).map(x => x * 10);
console.log("pipeline result ->", result.join(", "));
console.log("C++20 ranges express the same idea lazily");
Quiz

Ranges and views are useful because they:

A view often helps avoid:

Ranges are associated most strongly with:

03Capstone: Build Fast, Reusable Data Pipelines with STLCapstone Goal Build a realistic C++ data-processing or simulation utility that leans heavily on STL design instead of. The result should prove you can think like a modern. Use the right mix of sequence and associative containers Express core operatioadvanced

Capstone Goal Build a realistic C++ data-processing or simulation utility that leans heavily on STL design instead of. The result should prove you can think like a modern. Use the right mix of sequence and associative containers Express core operatio

Example
// Capstone checklist
[
  "container choices justified",
  "algorithms preferred over manual loops",
  "custom comparators written",
  "range pipeline included",
  "performance notes documented"
].forEach(item => console.log("[ ] " + item));
Quiz

A strong STL capstone demonstrates:

Manual loops should often give way to:

Performance reasoning in STL work includes: