Examples
C++ examples
Build fast applications with modern types and classes.
C++ Basics
Write and run a first program.
C++ conditions and range loops
Filter a sequence while accumulating a result.
C++ functions and references
Use a reference parameter to update a caller's value.
C++ recursive factorial
Trace recursive calls and their return values.
C++ strings and string streams
Use std::string, parse text with getline and istringstream, and convert between text and numbers.
C++ references, const, and auto
Pass large objects without copying, protect them with const, and let the compiler deduce types.
C++ lambdas and the standard algorithms
Sort, search, count, transform, and remove elements with algorithms and small anonymous functions.
C++ Classes
Group data and behavior.
C++ constructors and encapsulation
Initialize private state and expose a controlled interface.
C++ abstract classes and virtual dispatch
Invoke derived behavior through a base reference.
C++ composition and RAII
Let owned members manage their resources automatically.
C++ function templates
Reuse one type-checked algorithm for different types.
C++ inheritance and virtual functions
Call the right method through a base-class pointer, and see what slicing does.
C++ operator overloading
Give a Vec2 class natural arithmetic, comparison, and output operators.
C++ smart pointers and ownership
Use unique_ptr for single ownership, shared_ptr for shared ownership, and weak_ptr to observe.
C++ vectors and iterator invalidation
Grow a dynamic array and use checked access.
C++ binary search with lower_bound
Find an insertion position and check whether it is a match.
C++ stack and queue adapters
Compare LIFO and FIFO removal on the same values.
C++ ordered maps and frequencies
Count keys and traverse them in sorted order.
C++ linked lists with unique ownership
Build a node chain with automatic destruction.
C++ sorting: insertion sort, merge sort, and std::stable_sort
Write two sorts by hand and sort records with a comparator, keeping equal items in order.
C++ singly linked list with unique_ptr
Own each node with a unique_ptr, push at the front, reverse the list, and let destructors do the cleanup.
C++ binary search tree traversals
Insert values into a BST and visit them depth-first and level by level.
C++ priority_queue and the top-k pattern
Use a binary heap to get the smallest element quickly, and keep the k largest values of a stream.
C++ graphs: BFS, DFS, and connected components
Store a graph as adjacency lists, visit it breadth-first and depth-first, and count its components.
C++: best, worst, and average case of linear search
Count comparisons to see that one algorithm can have different costs on different inputs.
C++: amortized cost of a growing array
Count the copies made by a doubling array to see why push_back is amortized constant time.
C++: a hash join with unordered_map
Join two tables by building a hash table on one and probing it with each row of the other.
C++: an ordered index with std::map
Answer range and nearest-key queries with lower_bound and upper_bound.
C++: page replacement with FIFO and LRU
Count page faults for two replacement policies and see Belady's anomaly.
C++: protecting shared data with std::mutex
Run two threads that increment one counter and use a lock to keep every update.
C++: the Internet checksum
Compute the 16-bit ones'-complement checksum used by IP, TCP, and UDP, and use it to detect corruption.
C++: forwarding with longest-prefix match
Pick the most specific route that matches a destination address, as a router does.
C++: a small unit-test harness
Check results and expected exceptions with a macro and a template, and report failures.
C++: the observer pattern with std::function
Notify any number of listeners without the publisher knowing what they do.
C++: preventing buffer overflows with bounds checks
Reject writes that do not fit in a buffer and use at() so out-of-range reads fail safely.
C++: validating untrusted input with std::from_chars
Parse a port number strictly and reject anything that is not exactly a number in range.
C++: splitting a sum across std::async tasks
Run two halves of a computation concurrently and combine the results with futures.
C++: lock-free counting with std::atomic
Increment a shared counter from four threads without a mutex.
C++: A* search with a Manhattan-distance heuristic
Guide a shortest-path search with an estimate of the remaining distance.
C++: minimax with alpha-beta pruning
Search a game tree and skip branches that cannot change the result.
C++: entailment by enumerating models
Test whether a knowledge base entails a query by checking every truth assignment.
C++: backward chaining from a goal
Prove a goal by finding a rule that concludes it and then proving that rule's conditions.
C++: linear regression with gradient descent
Fit y = w·x + b by repeatedly moving the parameters against the gradient of the mean squared error.
C++: k-means clustering
Group unlabeled points by alternating between assigning points to centers and moving centers to the mean.
C++: a perceptron learns OR but not XOR
Train the same neuron on two gates and compare the accuracy it can reach.
C++: stable softmax and cross-entropy loss
Turn raw scores into probabilities, measure the loss, and avoid overflow.
C++: convolution with zero padding
Apply a Laplacian kernel so the output has the same size as the input and responds to a single bright pixel.
C++: grayscale conversion and thresholding
Convert color pixels to brightness with luminance weights and split them into foreground and background.