D Programming
In this tutorial I condense a 300 page book on the D programming language into one 1½ hour video. I cover all the basics along with more complex topics such as Recursion, Anonymous Functions, Map, Exceptions, Pointers, Inheritance, Polymorphism, Interfaces, Abstract Classes, Templates, Mixins, Threads and much more.
Timestamps for the whole video along with heavily commented code can be found below to help you learn and to act as a cheat sheet.
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Table of Contents
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01:12 User Input / Output 02:07 Compiling 02:25 Variables 02:44 Data Types / Formatted Output 06:18 Float Precision 08:30 Casting 10:50 Math 13:46 Date 14:43 Random Numbers 15:45 Arrays 20:48 Strings 24:37 Associative Arrays 26:47 More User Input 29:10 Conditionals 29:27 If / Else / Else If 30:52 Ternary Operator 31:25 Switch 33:16 For / Foreach Loop 36:18 While / Break / Continue 38:00 Do While 39:28 Functions 43:23 Recursion 45:10 In / Const / Out 46:35 Overloading 47:50 Tuples 50:15 Anonymous Functions 50:59 Map 52:28 Filter 53:09 Reduce 54:18 Generate 56:11 Enums 57:04 Exceptions 59:08 File IO 1:01:30 Pointers 1:03:18 Structs 1:06:26 Classes / Static/ This 1:11:52 Inheritance 1:15:53 Polymorphism 1:17:14 Interfaces 1:18:38 Abstract Classes 1:19:47 Templates 1:22:58 Mixins 1:25:09 Threads |
Code From the Video
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// Imports a module that contains functions // that handle input and output import std.stdio; import std.conv; import std.math; import std.random; import std.datetime; import std.algorithm; import std.array; import std.string; import std.format; import std.typecons : No; import std.typecons; import std.range : chain; import std.file; import core.thread; import std.parallelism; import std.concurrency; import std.range; // Best D Book // http://ddili.org/ders/d.en/index.html /* multiline comment */ // ---- FUNCTIONS ---- int getSum3(int x, int y){ return x + y; } double getSum3(double x, double y){ return x + y; } // The execution of your program begins at main void main(){ // ---- USER INPUT ---- // Read input from the user as a string // followed by a newline // string name; // write("What's your name? "); // readf("%s\n", &name); // // // Outputs the string contained to the // // terminal // writeln("Hello ", name); // ---- VARIABLES ---- // Variable names start with a letter and // can contain numbers and underscores int a1_B = 10; // ---- DATA TYPES ---- // Also ubyte, ushort, uint, ulong, // Imaginary : ifloat, idouble, ireal // Complex : cfloat, cdouble, creal // wchar : UTF-16 strings // dchar : UTF-32 strings // You can have the type picked for you auto bool1 = true; writeln("Bool : ", bool1); // booleans are either true or false // Formatted with %s writeln("int min : ", bool.min); writeln("int max : ", bool.max); bool happy = true; writefln("Bool : %s", happy); // chars are single characters surrounded // with single quotes // Can also store \n, \t, \b, \f, \r, \", // \', \\ writeln("char min : ", char.min); writeln("char max : ", char.max); char a = 'a'; writefln("Char : %c", a); // Formatting for integer types uses %d writeln("byte min : ", byte.min); writeln("byte max : ", byte.max); writeln("short min : ", short.min); writeln("short max : ", short.max); writeln("int min : ", int.min); writeln("int max : ", int.max); writeln("long min : ", long.min); writeln("long max : ", long.max); // You can use underscores long lNum = 123_456_789_100; // Shift right depending on the output writefln("lNum : %15d", lNum); writeln("float max : ", float.max); float fNum = 1.1111111111111111; float fNum2 = 1.1111111111111111; // Formats output to show 16 decimals // Floats are accurate to 6 decimals writefln("Float : %1.16f", fNum + fNum2); // Doubles are accurate to 15 writeln("double max : ", double.max); double dNum = 1.1111111111111111; double dNum2 = 1.1111111111111111; writefln("Double : %1.16f", dNum + dNum2); // Doubles are accurate to 19 writeln("real max : ", real.max); real rNum = 1.11111111111111111111; real rNum2 = 1.11111111111111111111; writefln("Real : %1.20f", rNum + rNum2); // Get default values writeln("Default int : ", int.init); // ---- CASTING ---- // You can convert from one type to another // Convert an int into a short int cInt = 15; short cShort = cast(short) cInt; // Casting causes issues if container is small short cShort2 = cast(short) 32768; writeln("Short Cast : ", cShort2); // Convert int to string and show type auto sInt = to!string(10); writeln("Type : ", typeof(sInt).stringof); // Convert string to int and show type auto iStr = to!int("10"); writeln("Type : ", typeof(iStr).stringof); // ---- MATH ---- writeln("5 + 4 = ", (5+4)); writeln("5 - 4 = ", (5-4)); writeln("5 * 4 = ", (5*4)); writeln("5 / 4 = ", (5/4)); writeln("5 % 4 = ", (5%4)); // Math done on integers default to // integer output and doubles return doubles writeln("5 / 4 = ",(5.0/4.0)); // incMe++ same as incMe = incMe + 1 // Can also decrement with -- int incMe = 0; writeln("incMe: ",(incMe++)); writeln("incMe: ",(++incMe)); // Another shortcut incMe += 10; // Numerous math functions writeln("abs(-1) = ", abs(-1)); writeln("ceil(4.25) = ", ceil(4.25)); writeln("floor(4.25) = ", floor(4.25)); writeln("round(4.25) = ", round(4.25)); writeln("exp(1.0) = ", exp(1.0)); writeln("log(1) = ", log(1)); writeln("log10(1) = ", log10(1)); writeln("pow(2,2) = ", pow(2,2)); writeln("sqrt(4) = ", sqrt(4.0)); writeln("cbrt(4) = ", cbrt(4.0)); writeln("hypot(5,5) = ", hypot(5,5)); writeln("PI = ", PI); // Trig Functions Radians writeln("sin(1.5708) = ", sin(1.5708)); writeln("cos(1.5708) = ", cos(1.5708)); writeln("tan(1.5708) = ", tan(1.5708)); writeln("asin(1.5708) = ", asin(1.5708)); writeln("acos(1.5708) = ", acos(1.5708)); writeln("atan(1.5708) = ", atan(1.5708)); writeln("sinh(1.5708) = ", sinh(1.5708)); writeln("cosh(1.5708) = ", cosh(1.5708)); writeln("tanh(1.5708) = ", tanh(1.5708)); // ---- DATE ---- auto nowTime = Clock.currTime(UTC()); writeln(nowTime.year); writeln(nowTime.month); writeln(nowTime.day); writeln(nowTime.hour); writeln(nowTime.minute); writeln(nowTime.second); // ---- RANDOM NUMBERS ---- // Generate random number from 5 to 20 // Generate random seed int seed = nowTime.second; auto rand = Random(seed); writeln("Rand : ", uniform(5, 20, rand)); // ---- ARRAYS ---- // Arrays store multiple values in boxes // in memory // Fixed size array int[10] a1; // Set values int[] a2 = [1,2,3,4]; // Change using index a2[0] = 0; // Get value with index writeln("Index : ", a2[0]); // Create a resizable array (Dynamic) int[] a3; // Add values a3 ~= 1; a3 ~= 2; a3 ~= 3; // Remove an index a3 = a3.remove(1); writeln(a3); // Combine arrays a3 = a2 ~ a3; writeln(a3); // Get odds a3 = a3.remove!(x => (x%2) == 0); writeln(a3); // Sort and reverse writeln(sort(a3)); writeln(reverse(a3)); // Replace all matches writeln(a3.replace(3,2)); // Get a range of values a3 = a2 ~ a3; writeln(a3[0 .. 3]); // Duplicate array auto a4 = a3.dup; // Perform operation on every value a4[] *= 2; writeln(a4); // Multidimensional array // a5[How many down][How many across][How many Groups] // a5[3][4][1] string[][][] a5 = [[["000"], ["100"], ["200"], ["300"]], [["010"], ["110"], ["210"], ["310"]], [["020"], ["120"], ["220"], ["320"]]]; writeln(a5[2][3][0]); // ---- STRINGS ---- // Strings are arrays of characters but // the character values can't be changed string s1 = "Doug"; // Would throw an error // s1[0] = 'T'; // You can get the character writeln(s1[0]); // You can change the string in whole s1 = "Tom"; // Get size writeln("Size : ", s1.length); // Combine strings string s2 = s1 ~ " Thumb"; // Find index writeln("T : ", indexOf(s2, 'T')); writeln("Last T : ", lastIndexOf(s2, 'T')); writeln("Thumb : ", indexOf(s2, "Thumb", No.caseSensitive)); // Find and replace writeln(replace(s2, "Tom", "Ed")); // Convert string to array string s3 = "1 2 3"; auto numArr = to!(int[])(split(s3)); writeln(numArr); // Check equality string s4 = "1 2 3"; writeln(s3 == s4); // Convert upper and lower writeln(toUpper(s2)); writeln(toLower(s2)); // Is it a number writeln(isNumeric("10")); // ---- ASSOCIATIVE ARRAYS ---- // Key value pairs double[string] favNums = ["AZero" : -459, "Euler" : 2.7182]; // Add a key / value favNums["PI"] = 3.14159; favNums["Golden"] = 1.61803; // Get values writeln(favNums); writeln(favNums["Golden"]); // Number of values writeln(favNums.length); // Get keys and values writeln(favNums.keys); writeln(favNums.values); // Check if key exists and delete if("AZero" in favNums){ favNums.remove("AZero"); } writeln(favNums); // ---- MORE USER INPUT ---- // readln reads until the end of the line // and stores input in an array (Boxes in memory // for each character) // char[] arrName; // write("What's your name? "); // readln(arrName); // // strip deletes the newline at the end of array // writeln("Hello ", strip(arrName)); // // Read in multiple values at once // write("Enter 1st & last name? "); // string fName = strip(readln()); // string fN, lN; // // Define the input you expect 2 strings // // separated by a space // formattedRead(fName, " %s %s", // fN, lN); // writeln("Hello ", fN, " ", lN); // ---- CONDITIONALS ---- // Relational Operators : > < >= <= == != // Logical Operators : && || ! int age = 12; if ((age >= 5) && (age <= 6)){ writeln("Go to Kindergarten"); } else if ((age >= 7) && (age <= 13)){ writeln("Go to Middle School"); } else if ((age >= 14) && (age <= 18)){ writeln("Go to High School"); } else { writeln("Stay Home"); } writeln("true || false = ", (true || false)); writeln("!true = ", (!true)); // The ternary operator returns the 1st value // when the condition is true and the 2nd // otherwise bool canVote = (age >= 18) ? true : false; writeln("Can Vote : ",canVote); // Switch works great with limited options string lang = "France"; switch(lang){ case "Chile": case "Cuba": writeln("Hola"); break; case "France": writeln("Bonjour"); // Use goto to check the next goto case; case "Japan": writeln("Konnichiwa"); break; default: writeln("Hello"); } // You can also use ranges int anAge = 7; switch(anAge){ case 7: .. case 13: writeln("Go to middle school"); break; default: writeln("Somewhere else"); } // ---- LOOPING ---- // For loop for(int i = 0; i < 5; i++){ writeln(i); } // foreach is more commonly used // for containers int[] a6 = [1,2,3,4]; foreach(x; a6){ writeln(x); } // Work with ranges foreach(x; 5..10){ writeln(x); } // Associative Arrays double[string] aA = ["A" : 1, "B" : 2]; // Keys and values foreach(k, v; aA){ writeln(k, " ", v); } // Get both as a group foreach(x; aA.byKeyValue){ writefln("%s : %s", x.key, x.value); } // You are working with copies by default int[] fE1 = [1,2,3,4]; foreach(x; fE1){ x *= 2; } writeln(fE1); // Using reference changes values foreach(ref x; fE1){ x *= 2; } writeln(fE1); // While executes as long as a condition // is true int wI = 0; while (wI < 20) { // Only print even numbers if(wI % 2 == 0) { writeln(wI); wI++; // Jump back to the beginning of loop continue; } if(wI >= 10) { // Stop looping break; } wI++; } // Do While always executes once // int secretNum = 7; // int guess = 0; // do { // write("Guess : "); // readf("%d\n", &guess); // }while(secretNum != guess); // writeln("You guessed it"); // ---- FUNCTIONS ---- // Function definitions follow the format // returnType functionName(parameterType parameterName) int getSum(int x, int y){ return x + y; } writeln("5 + 4 = ", getSum(5,4)); // Variables changed in functions don't // effect values outside of it unless // you use ref void changeMe(ref int f1){ f1 = 5; } int f1 = 10; changeMe(f1); writeln("f1 : ", f1); // Receive a variable number of arguments int getSum2(A...)(A args){ int sum = 0; foreach(x; args){ sum += x; } return sum; } writeln("Sum : ", getSum2(1,2,3,4)); // Return multiple values with an array int[] getNext2(int x){ int[] next2 = [x+1, x+2]; return next2; } int[] next2 = getNext2(1); writeln(next2); // Recursion : Function calls self int fact(int num){ // Must have a condition were we don't // call for the function to execute if(num == 1){ return 1; } else { int result = num * fact(num - 1); return result; } } writeln("Fact 4 : ", fact(4)); // 1st : result = 4 * factorial(3) = 4 * 6 = 24 // 2nd : result = 3 * factorial(2) = 3 * 2 = 6 // 3rd : result = 2 * factorial(1) = 2 * 1 = 2 // Arguments marked with in can't be changed // The same is true with const void randFunc(in int x, const int y){ // Will cause error -> x = 1; } // out returns values to parameters void randFun2(out int f2){ f2 = 100; } int f2 = 5; randFun2(f2); writeln("f2 : ", f2); // You can overload functions by // having different parameter types writeln("5.4 + 4.5 = ", getSum3(5.4,4.5)); // ---- TUPLES ---- // Used to store a key/value at once auto t1 = tuple("A",1); writeln(t1); // You can store more than 2 values auto t2 = tuple("B", 2, 5.6); writeln(t2); // Change values t2[0] = "A"; // Get values by index writeln(t2[0]); // You can pass multiple values into // functions void printTuple(string s, int i){ writeln(s, " ", i); } printTuple(t1.expand); // You can also return multiple values Tuple!( int, string ) returnTuple(){ return tuple(5, "Hello"); } auto t3 = returnTuple(); writeln(t3); // ---- ANONYMOUS FUNCTIONS & // SEQUENCE PROCESSING ---- // Allow you to define a function inside // an expression auto aF1 = (int a) => a * 2; writeln(aF1(5)); // Use map to multiply all by 2 int[] a7 = [1,2,3,4]; auto aF2 = map!(a => a * 2)(a7); writeln(aF2); // Combine arrays and do the same int[] a8 = [5,6,7]; auto aF3 = map!(a => a * 2)(chain(a7,a8)); writeln(aF3); // Use filter to get evens auto aF4 = a7.filter!(a => (a % 2) == 0); writeln(aF4); // Use reduce to add values auto aF5 = reduce!((a,b) => a + b)(0,a7); writeln(aF5); // Get max auto aF6 = reduce!(max)(aF3); writeln(aF6); // Generate a random range auto now2 = Clock.currTime(UTC()); auto seed2 = now2.second; auto rand2 = Random(seed2); auto randVals = generate!(() => uniform(1, 2000, rand2))().take(10); foreach(x; randVals){ writeln(x); } // ---- ENUM ---- // Custom type made up of named constants enum Suit {club, diamond, heart, spade} Suit card = Suit.heart; writeln(card); // ---- EXCEPTIONS ---- // Through exception handling you can // block potential errors. You wouldn't // normally handle divide by zero errors // this way, but this is an easy example // to understand // Wrap problematic code with try try{ int zero = 0; // assert can be used to test assumptions // during the development process // assert(zero != 0, "Can't be zero"); if (zero == 0){ // Throw error to be handled throw new Exception("Can't divide by zero"); } else { int badInt = 10 / zero; } } // Will catch any exception as well as // yours and print a message rather than // crashing catch(Exception e){ writeln(e.msg); } // Close files, databases, etc. here finally{ writeln("Cleaning up"); } // ---- FILE IO ---- // Open a file for writing // w : Open for writing and/or create file // a : Open for appending and/or create file // r : Open for reading // r+ : Open for reading and writing // w+ : Reading and writing, 0 file, or create // a+ : Reading and append writing File file = File("myfile.txt", "w"); file.writeln("Some random text"); file.writeln("More random text"); file.close(); // Open for reading File file2 = File("myfile.txt", "r"); // As long as their are lines print them while(!file2.eof()){ writeln(chomp(file2.readln())); } file2.close(); // ---- POINTERS ---- // You can work with pointers like C // A pointer stores the address of a // variables data in memory int val = 43; // Store the address by placing the // reference operator before the variable int* pVal = &val; // Get the address writeln("Address : ", pVal); // Get the value stored there writeln("Value : ", *pVal); // Pass a pointer to a function void changePtrVal(int* pVal){ *pVal = 22; } changePtrVal(&val); writeln("Value : ", val); // ---- STRUCTS ---- // Structs are custom types that // combine other types of data struct Customer{ string name; string phone; double bal = 0; // Static variables are part of the struct static numCusts = 0; } // Create and add data Customer c1; c1.name = "Paul Smith"; c1.phone = "555-1212"; c1.bal = 340.10; Customer.numCusts++; writefln("Call %s at %s about $%.2f", c1.name, c1.phone, c1.bal); // Create on one line Customer c2 = {"Sue Smith", "555-1213", 18.90}; Customer.numCusts++; writeln("Number of custs : ", Customer.numCusts); // ---- CLASSES ---- // Classes model real world objects / systems // by storing their attributes and // simulating their capabilities // Classes limit access to data (Encapsulation) // Allow fields and methods to be Inherited // Allow subclasses to be treated as super // classes while maintaining changes in the subclasses // Polymorphism class Animal{ string name; double height; double weight; string sound; // static fields belong to the class // and their values are shared by all // objects static int numOfAnimals; // Function called when Animal objects // are created this(string name, double height, double weight, string sound){ // this allows us to refer to the // object even though we don't know // its name this.name = name; this.height = height; this.weight = weight; this.sound = sound; numOfAnimals++; } // If this was final void makeSound // I couldn't override it void makeSound(){ writeln(this.name, " says ", this.sound); } void getInfo(){ writefln("%s is %.2f inches %.2f lbs and says %s", this.name, this.height, this.weight, this.sound); } // static methods are normally utility functions // that it wouldn't make sense for the object // to be able to perform but you need it static void getNumOfAnimals(){ writeln("Num of Animals : ", numOfAnimals); } } // I can inherite everything is Animal // and make changes as I wish // You can only inherit 1 class class Dog : Animal{ string owner; // Have the Animal constructor initialize // all fields in both this(string name, double height, double weight, string sound, string owner){ super(name, height, weight, sound); this.owner = owner; } // Override get info override void getInfo(){ super.getInfo(); writefln("%s's owner is %s", this.name, this.owner); } } Animal jake = new Animal("Jake", 35, 140, "Woof"); jake.getInfo(); Dog paul = new Dog("Paul", 20, 85, "Grrr", "Robert Hansen"); paul.getInfo(); // As long as the same methods exist // in the super class and the subclass // you can refer to the subclass as // if it is its super class type // Polymorphism Animal john = new Dog("John", 20, 85, "Grrr", "Larry Eyler"); john.getInfo(); john.getNumOfAnimals(); // If you want to add functionality to // a class and it doesn't make sense for // that functionality to be made into an // object you may need an interface interface Drivable{ // You define, but don't implement methods // in an interface void move(); void stop(); } // You can implement multiple interfaces by // just separating them with a comma class Vehicle : Drivable{ void move(){} void stop(){} } // Abstract classes define functions that // must be implemented, but they can also // define implementation unlike interfaces class Flyable{ abstract void fly(){ writeln("I'm flying"); } abstract void crash(); } // ---- TEMPLATES ---- // Templates allow you to define algorithms // that work with multiple data types void getSum4(T)(T x, T y){ writeln(x, " + ", y, " = ", x + y); } getSum4(4,6); getSum4(4.5, 5.6); // You can use templates any place you define types // You can define a template block of code template tempSamp(T){ struct Shape{ T height; T width; } T getArea(Shape shape){ return shape.height * shape.width; } } auto shape = tempSamp!int.Shape(4,5); writeln("Area : ", tempSamp!int.getArea(shape)); // ---- MIXINS ---- // Mixins allow you to generate code // at run time // Generate int var1 = 10; mixin MakeType!(int, 10); writeln(var1); // Generate a function mixin GetSum!(double); writeln("1.2 + 2.3 = ", add(1.2,2.3)); // ---- THREADS ---- // A thread is a block of code that is expected // to execute while other blocks of code execute // Let's run different blocks pausing as we go // void doStuff(int x){ // writeln(x, " start"); // Thread.sleep(1.seconds); // writeln(x, " stops"); // } // // auto now1 = Clock.currTime(UTC()); // auto sS = now1.second; // // doStuff(1); // doStuff(2); // doStuff(3); // // auto now2 = Clock.currTime(UTC()); // auto sS2 = now2.second; // writeln("Seconds : ", sS2 - sS); class Worker{ int id; this(int id){ this.id = id; } void work(){ // Get thread id writeln(id, " : ", thisTid); writeln("Thread ", id, " starts"); Thread.sleep(1.seconds); writeln("Thread ", id, " ends"); } } // Total cores writeln("Cores : ", totalCPUs); auto workers = [new Worker(0), new Worker(1), new Worker(2)]; // Parallel will execute the functions in parallel foreach(w; parallel(workers)){ w.work(); } } // ---- MIXINS ---- mixin template MakeType(T, T x){ T var1 = x; } mixin template GetSum(T){ T add(T x, T y){ return x + y; } } |
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