Intermediate C++ Game Programming Tutorial 16

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In the video we take a look at a couple of bangers from <algorithm>, and we learn what lambda functions are and how to use them.

Topics Covered

  • Algorithms std::sort and std::remove_if
  • Concepts (as in, type concepts like Comparable)
  • <functional> functors as predicates
  • Lambda functions

Errata

In the video Chili states that std::remove does not preserve the relative order of elements in the container, but this is fake news! Relative order is preserved: [1]

Video Timestamp Index

Tutorial 16

  • Generic Algorithms: how Templates and Iterators make Algorithms independent of Data Types and Containers 0:17
  • The std::sort algorithm and its requirements 0:43
  • Sorting a (forward) list std::list, using its member function std::list::sort() 2:16
  • Introducing Concepts / named requirements of types (e.g., the Compare requirement of std::sort 2:54
  • Modyfing sorting order by passing a comparison function object (functor) as a predicate, like so:
    std::sort(vec.begin(),vec.end(),std::greater<int>{}); 3:17
    Note: vec is a std::vector of integers
  • Sort custom types, example code for sorting a custom class object by creating a functor, called like so:
    std::sort(vecObj.begin(),vecObj.end(),Obj::YLess{}); 4:07
  • Removing items from a container, std::remove and std::remove_if 6:11
    - Create a functor as a unary predicate for the remove function to remove elements using a threshold variable 8:28
    - Use container member function erase() to correct the endpoint of the container iterator after the remove operation 9:51
  • [WORK-IN-PROGRESS]

Homework

Solve the problems in Source.cpp attached below using the <algorithm> library and other parts of the standard library as extensively as possible. As a bonus problem, implement the sprite drawing effect shown at the end of the video using a lambda function.

Related Series

For an in-depth look into the <algorithm> library and beyond, check out STD Gems.

Links

Algorithms Library

See also