Tutorial by Examples: ar

Compiler warnings can be generated using the #warning directive, and errors can likewise be generated using the #error directive. #if SOME_SYMBOL #error This is a compiler Error. #elif SOME_OTHER_SYMBOL #warning This is a compiler Warning. #endif

Array types inherit their equals() (and hashCode()) implementations from java.lang.Object, so equals() will only return true when comparing against the exact same array object. To compare arrays for equality based on their values, use java.util.Arrays.equals, which is overloaded for all array types...

Swift's C interoperability allows you to use functions and types from the C standard library. On Linux, the C standard library is exposed via the Glibc module; on Apple platforms it's called Darwin. #if os(macOS) || os(iOS) || os(tvOS) || os(watchOS) import Darwin #elseif os(Linux) import Glibc...

dynamic foo = 123; Console.WriteLine(foo + 234); // 357 Console.WriteLine(foo.ToUpper()) // RuntimeBinderException, since int doesn't have a ToUpper method foo = "123"; Console.WriteLine(foo + 234); // 123234 Console.WriteLine(foo.ToUpper()): // NOW A STRING

Arrays of anonymous types may be created with implicit typing. var arr = new[] { new { Id = 0 }, new { Id = 1 } };

C11 C11 introduced support for multiple threads of execution, which affords the possibility of data races. A program contains a data race if an object in it is accessed1 by two different threads, where at least one of the accesses is non-atomic, at least one modifies the object, and program seman...

The typeof operator works on type parameters. class NameGetter<T> { public string GetTypeName() { return typeof(T).Name; } }

git bisect allows you to find which commit introduced a bug using a binary search. Start by bisecting a session by providing two commit references: a good commit before the bug, and a bad commit after the bug. Generally, the bad commit is HEAD. # start the git bisect session $ git bisect start ...

To explicitly declare variables in VBA, use the Dim statement, followed by the variable name and type. If a variable is used without being declared, or if no type is specified, it will be assigned the type Variant. Use the Option Explicit statement on first line of a module to force all variables t...

SQL injection is a kind of attack that allows a malicious user to modify the SQL query, adding unwanted commands to it. For example, the following code is vulnerable: // Do not use this vulnerable code! $sql = 'SELECT name, email, user_level FROM users WHERE userID = ' . $_GET['user']; $conn->...

The return type of a method can depend on the type of the parameter. In this example, x is the parameter, A is the type of x, which is known as the type parameter. def f[A](x: A): A = x f(1) // 1 f("two") // "two" f[Float](3) // 3.0F Scala will use type infe...

The getAll() method retrieves all values from the preferences. We can use it, for instance, to log the current content of the SharedPreferences: private static final String PREFS_FILE = "MyPrefs"; public static void logSharedPreferences(final Context context) { SharedPreferences s...

CREATE TABLE Person ( PersonID INT UNSIGNED NOT NULL, LastName VARCHAR(66) NOT NULL, FirstName VARCHAR(66), Address VARCHAR(255), City VARCHAR(66), PRIMARY KEY (PersonID) ); A primary key is a NOT NULL single or a multi-column identifier whic...

Java SE 8 Converting an array of objects to Stream: String[] arr = new String[] {"str1", "str2", "str3"}; Stream<String> stream = Arrays.stream(arr); Converting an array of primitives to Stream using Arrays.stream() will transform the array to a primitive sp...

Sometimes you may want to start a new activity while removing previous activities from the back stack, so the back button doesn't take you back to them. One example of this might be starting an app on the Login activity, taking you through to the Main activity of your application, but on logging out...

The built-in mtcars data frame contains information about 32 cars, including their weight, fuel efficiency (in miles-per-gallon), speed, etc. (To find out more about the dataset, use help(mtcars)). If we are interested in the relationship between fuel efficiency (mpg) and weight (wt) we may start p...

Dim array(9) As Integer ' Defines an array variable with 10 Integer elements (0-9). Dim array = New Integer(10) {} ' Defines an array variable with 11 Integer elements (0-10) 'using New. Dim array As Integer() = {1, 2, 3, 4} ' Defines an Integer array variable a...

Adding elements: [1, 2, 3] << 4 # => [1, 2, 3, 4] [1, 2, 3].push(4) # => [1, 2, 3, 4] [1, 2, 3].unshift(4) # => [4, 1, 2, 3] [1, 2, 3] << [4, 5] # => [1, 2, 3, [4, 5]] Removing elements: array = [1, 2, 3, 4] array.pop # => 4 array # => [1, 2, 3] ...

Functions can take inputs in form of variables that can be used and assigned inside their own scope. The following function takes two numeric values and returns their sum: function addition (argument1, argument2){ return argument1 + argument2; } console.log(addition(2, 3)); // -> 5 ...

x = [5, 5, 1, 3] y = [5, 2, 4, 3] Union (|) contains elements from both arrays, with duplicates removed: x | y => [5, 1, 3, 2, 4] Intersection (&) contains elements which are present both in first and second array: x & y => [5, 3] Difference (-) contains elements which ar...