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Arrays in C can be seen as a contiguous chunk of memory. More precisely, the last dimension of the array is the contiguous part. We call this the row-major order. Understanding this and the fact that a cache fault loads a complete cache line into the cache when accessing uncached data to prevent sub...

You can order ActiveRecord query results by using .order: User.order(:created_at) #=> => [#<User id: 2, created_at: "2015-08-12 21:36:23">, #<User id: 11, created_at: "2015-08-15 10:21:48">] If not specified, ordering will be performed in ascending order. Y...

When you have a variable containing a struct, you can access its fields using the dot operator (.). However, if you have a pointer to a struct, this will not work. You have to use the arrow operator (->) to access its fields. Here's an example of a terribly simple (some might say "terribl...

Enums can have custom init methods that can be more useful than the default init?(rawValue:). Enums can also store values as well. This can be useful for storing the values they where initialized with and retrieving that value later. enum CompassDirection { case north(Int) case south(Int)...

[HttpPost] public ActionResult ContactUs(ContactUsModel contactObject) { // This line checks to see if the Model is Valid by verifying each Property in the Model meets the data validation rules if(ModelState.IsValid) { } return View(contactObject); } The model class p...

Build a text report showing the main classification metrics, including the precision and recall, f1-score (the harmonic mean of precision and recall) and support (the number of observations of that class in the training set). Example from sklearn docs: from sklearn.metrics import classification_re...

Groovy has access to all java classes, in fact Groovy classes ARE Java classes and can be run by the JVM directly. If you are working on a Java project, using Groovy as a simple scripting language to interact with your java code is a no-brainer. To make things even better, nearly any Java class ca...

String literals represent null-terminated, static-duration arrays of char. Because they have static storage duration, a string literal or a pointer to the same underlying array can safely be used in several ways that a pointer to an automatic array cannot. For example, returning a string literal f...

The when-statement is an alternative to an if-statement with multiple else-if-branches: when { str.length == 0 -> print("The string is empty!") str.length > 5 -> print("The string is short!") else -> print("The string is long!") ...

When given an argument, the when-statement matches the argument against the branches in sequence. The matching is done using the == operator which performs null checks and compares the operands using the equals function. The first matching one will be executed. when (x) { "English" -...

(This pitfall applies equally to all primitive wrapper types, but we will illustrate it for Integer and int.) When working with Integer objects, it is tempting to use == to compare values, because that is what you would do with int values. And in some cases this will seem to work: Integer int1_1 =...

The .format() method can interpret a number in different formats, such as: >>> '{:c}'.format(65) # Unicode character 'A' >>> '{:d}'.format(0x0a) # base 10 '10' >>> '{:n}'.format(0x0a) # base 10 using current locale for separators '10' Format integers to d...

union U { int a; short b; float c; }; U u; u.a = 10; if (u.b == 10) { // this is undefined behavior since 'a' was the last member to be // written to. A lot of compilers will allow this and might issue a // warning, but the result will be "as expected"; thi...

Properties can be set when an object is instantiated. var redCar = new Car { Wheels = 2, Year = 2016, Color = Color.Red };

If you know that a value is of a specific type, you can explicitly cast it to that type in order to use it in a context where that type is needed. object value = -1; int number = (int) value; Console.WriteLine(Math.Abs(number)); If we tried passing value directly to Math.Abs(), we would get a ...

If you aren't sure whether a value is of the type you think it is, you can safely cast it using the as operator. If the value is not of that type, the resulting value will be null. object value = "-1"; int? number = value as int?; if(number != null) { Console.WriteLine(Math.Abs(nu...

A value will automatically be cast to the appropriate type if the compiler knows that it can always be converted to that type. int number = -1; object value = number; Console.WriteLine(value); In this example, we didn't need to use the typical explicit casting syntax because the compiler knows...

If you need to know whether a value's type extends or implements a given type, but you don't want to actually cast it as that type, you can use the is operator. if(value is int) { Console.WriteLine(value + "is an int"); }

In the most basic form, it is possible to select a single variable from a table by calling the object's get_var method passing in an SQL query. global $wpdb; $user = $wpdb->get_var( "SELECT ID FROM $wpdb->users WHERE user_email='[email protected]'" ); It is very important to note that...

public class Singleton { private static class InstanceHolder { static final Singleton INSTANCE = new Singleton(); } public static Singleton getInstance() { return InstanceHolder.INSTANCE; } private Singleton() {} } This initializes the INSTANCE vari...