C++ Tutorial 14
In this tutorial I cover many topics many people have asked for. I show how to include outside files, Preprocessor Directives, Macro Constants, Macro Functions, Template Functions, Template Classes, and Iterators.
Like always all of the code follows the video below. It is heavily commented and it is recommended to print it out and take notes on it as you watch.
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Code from the Video
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——- ANIMAL.H ——- // This guards against including this header in multiple // files that make up the program along with #endif #ifndef ANIMAL_H // Read the following lines once #define ANIMAL_H #include <string> class Animal { public: Animal(); Animal(const Animal& orig); virtual ~Animal(); std::string name; private: }; #endif /* ANIMAL_H */ ——- ANIMAL.CPP ——- #include "Animal.h" Animal::Animal() { } Animal::Animal(const Animal& orig) { } Animal::~Animal() { } #include <cstdlib> #include <iostream> #include <string> #include <vector> #include <ctime> #include <numeric> #include <cmath> #include <sstream> #include <deque> #include <iterator> // ----- PREPROCESSOR DIRECTIVES ----- // Anything that starts with a # is a preprocessor // directive and they run before the program compiles // Right click Header Files -> New -> C++ Header File // and then include it here #include "Animal.h" // This is a macro constant that will replace // PI with 3.14159 in the code before execution #define PI 3.14159 // This is a macro function that will do the same with // a function #define AREA_CIRCLE(radius) (PI * (std::pow(radius, 2))) // ----- END PREPROCESSOR DIRECTIVES ----- // ----- TEMPLATE FUNCTIONS ----- // We use templates to create functions or classes // that can work with many types // Templates differ from function overloading in that // instead of having a function that does similar // things with different objects a template does the // same thing with different objects // This says this is a function template that generates // functions that except 1 parameter template <typename T> void Times2(T val){ std::cout << val << " * 2 = " << val * 2 << "\n"; } // Receive multiple parameters and return a value template <typename T> T Add(T val, T val2){ return val + val2; } // Work with chars and strings template <typename T> T Max(T val, T val2){ return (val < val2) ? val2 : val; } // ----- END OF TEMPLATE FUNCTIONS ----- // ----- TEMPLATE CLASSES ----- // Template classes are classes that can work with // different data types // You can define that you may receive parameters // with different types, but they don't have to // be different template <typename T, typename U> class Person{ public: T height; U weight; static int numOfPeople; Person(T h, U w){ height = h, weight = w; numOfPeople++; } void GetData(){ std::cout << "Height : " << height << " and Weight : " << weight << "\n"; } }; // You have to initialize static class members template<typename T, typename U> int Person<T, U>::numOfPeople; // ----- END OF TEMPLATE CLASSES ----- int main() { Animal spot = Animal(); spot.name = "Spot"; std::cout << "The Animal is named " << spot.name << "\n"; std::cout << "Circle Area : " << AREA_CIRCLE(5) << "\n"; // ----- TEMPLATE FUNCTIONS ----- // The template function can receive ints or floats Times2(5); Times2(5.3); // Multiple parameters and returned value std::cout << "5 + 4 = " << Add(5,4) << "\n"; std::cout << "5.5 + 4.6 = " << Add(5.5,4.6) << "\n"; // Get biggest value std::cout << "Max 4 or 8 = " << Max(4, 8) << "\n"; std::cout << "Max A or B = " << Max('A', 'B') << "\n"; std::cout << "Max Dog or Cat = " << Max("Dog", "Cat") << "\n"; // ----- END OF TEMPLATE FUNCTIONS ----- // ----- TEMPLATE CLASSES ----- // When creating the object you must define the // data types used Person<double, int> mikeTyson (5.83, 216); mikeTyson.GetData(); // You access static values using the object // and not the class std::cout << "Number of people : " << mikeTyson.numOfPeople << "\n"; // ----- END OF TEMPLATE CLASSES ----- // ----- CONTAINERS ----- // We have already seen the STL container vector // There are many other special ways of storing data // ----- DOUBLE ENDED QUEUE ----- // A double ended queue (Deck) is a dynamic array that can // be expanded or contracted on both ends std::deque<int> nums = {1,2,3,4}; nums.push_front(0); nums.push_back(5); for(int x: nums) std::cout << x << "\n"; // You can access index values, but they are costly // because values aren't stored contigously, but // instead use multiple arrays std::cout << nums[0] << "\n"; // ----- END DOUBLE ENDED QUEUE ----- // ----- ITERATORS ----- // Iterators are used to point at container // memory locations std::vector<int> nums2 = {1,2,3,4}; // Define an iterator as the same type std::vector<int>::iterator itr; // Refer to the vectors begin and end while // incrementing the iterator for(itr = nums2.begin(); itr < nums2.end(); itr++){ // Get value at the pointer std::cout << *itr << "\n"; } // You can also increment a set number of spaces // Create an iterator and point it at the beginning // of the vector std::vector<int>::iterator itr2 = nums2.begin(); // Advance 2 spaces advance(itr2, 2); std::cout << *itr2 << "\n"; // Next works like advance, but it returns an // iterator auto itr3 = next(itr2, 1); std::cout << *itr3 << "\n"; // Previous moves a set number of indexes and // returns an iterator auto itr4 = prev(itr2, 1); std::cout << *itr4 << "\n"; // You can also insert at a defined index std::vector<int> nums3 = {1,4,5,6}; std::vector<int> nums4 = {2,3}; auto itr5 = nums3.begin(); advance(itr5, 1); copy(nums4.begin(), nums4.end(), inserter(nums3, itr5)); for(int &i: nums3) std::cout << i << "\n"; // ----- END ITERATORS ----- // ----- END OF CONTAINERS ----- return 0; } |
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