Tutorial by Examples: s

// lambda expressions can have explicitly annotated return types let floor_func = |x: f64| -> i64 { x.floor() as i64 };

Since lambda functions are values themselves, you store them in collections, pass them to functions, etc like you would with other values. // This function takes two integers and a function that performs some operation on the two arguments fn apply_function<T>(a: i32, b: i32, func: T) -> ...

Returning lambdas (or closures) from functions can be tricky because they implement traits and thus their exact size is rarely known. // Box in the return type moves the function from the stack to the heap fn curried_adder(a: i32) -> Box<Fn(i32) -> i32> { // 'move' applies move se...

State in React components is essential to manage and communicate data in your application. It is represented as a JavaScript object and has component level scope, it can be thought of as the private data of your component. In the example below we are defining some initial state in the constructor f...

The primary way that you make UI updates to your React applications is through a call to the setState() function. This function will perform a shallow merge between the new state that you provide and the previous state, and will trigger a re-render of your component and all decedents. Parameters ...

If no ordering function is passed, std::sort will order the elements by calling operator< on pairs of elements, which must return a type contextually convertible to bool (or just bool). Basic types (integers, floats, pointers etc) have already build in comparison operators. We can overload this ...

// Include sequence containers #include <vector> #include <deque> #include <list> // Insert sorting algorithm #include <algorithm> class Base { public: // Constructor that set variable to the value of v Base(int v): variable(v) { } i...

C++11 // Include sequence containers #include <vector> #include <deque> #include <list> #include <array> #include <forward_list> // Include sorting algorithm #include <algorithm> class Base { public: // Constructor that set variable to the va...

BigInteger is in an immutable object, so you need to assign the results of any mathematical operation, to a new BigInteger instance. Addition: 10 + 10 = 20 BigInteger value1 = new BigInteger("10"); BigInteger value2 = new BigInteger("10"); BigInteger sum = value1.add(value...

Model with ForeignKey We will work with these models : from django.db import models class Book(models.Model): name= models.CharField(max_length=50) author = models.ForeignKey(Author) class Author(models.Model): name = models.CharField(max_length=50) Suppose we often (always) access ...

You can access each property that belongs to an object with this loop for (var property in object) { // always check if an object has a property if (object.hasOwnProperty(property)) { // do stuff } } You should include the additional check for hasOwnProperty because an o...

It is undefined behavior to access an index that is out of bounds for an array (or standard library container for that matter, as they are all implemented using a raw array): int array[] = {1, 2, 3, 4, 5}; array[5] = 0; // Undefined behavior It is allowed to have a pointer pointing to the en...

pip may be used to install BeautifulSoup. To install Version 4 of BeautifulSoup, run the command: pip install beautifulsoup4 Be aware that the package name is beautifulsoup4 instead of beautifulsoup, the latter name stands for old release, see old beautifulsoup

Here is an example class which has a couple of instance variables, without using properties: @interface TestClass : NSObject { NSString *_someString; int _someInt; } -(NSString *)someString; -(void)setSomeString:(NSString *)newString; -(int)someInt; -(void)setSomeInt:(NSString *)...

The default property getters and setters can be overridden: @interface TestClass @property NSString *someString; @end @implementation TestClass // override the setter to print a message - (void)setSomeString:(NSString *)newString { NSLog(@"Setting someString to %@", newS...

The syntax for Java generics bounded wildcards, representing the unknown type by ? is: ? extends T represents an upper bounded wildcard. The unknown type represents a type that must be a subtype of T, or type T itself. ? super T represents a lower bounded wildcard. The unknown type repres...

A belongs_to association sets up a one-to-one connection with another model, so each instance of the declaring model "belongs to" one instance of the other model. For example, if your application includes users and posts, and each post can be assigned to exactly one user, you'd declare th...

A has_one association sets up a one-to-one connection with another model, but with different semantics. This association indicates that each instance of a model contains or possesses one instance of another model. For example, if each user in your application has only one account, you'd declare the...

A has_many association indicates a one-to-many connection with another model. This association generally is located on the other side of a belongs_to association. This association indicates that each instance of the model has zero or more instances of another model. For example, in an application ...

For programmers coming from GCC or Clang to Visual Studio, or programmers more comfortable with the command line in general, you can use the Visual C++ compiler from the command line as well as the IDE. If you desire to compile your code from the command line in Visual Studio, you first need to set...