Tutorial by Examples: num

Implementing the IEnumerable interface allows classes to be enumerated in the same way as BCL collections. This requires extending the Enumerator class which tracks the state of the enumeration. Other than iterating over a standard collection, examples include: Using ranges of numbers based on a...

ForEach() is defined on the List<T> class, but not on IQueryable<T> or IEnumerable<T>. You have two choices in those cases: ToList first The enumeration (or query) will be evaluated, copying the results into a new list or calling the database. The method is then called on each it...

The random() function can be used to generate pseudo-random numbers: void setup() { Serial.begin(9600); } void loop() { long randomNumber = random(500); // Generate a random number between 0 and 499 Serial.println(randomNumber); randomNumber = random(100, 1000); // Genera...

For performance reasons you should minimize the number of fields you are requesting from the API. You can use the select property to do so. This example fetches the name property of all accounts: $.ajax({ url: Xrm.Page.context.getClientUrl() + '/api/data/v8.0/accounts?$select=name', head...

Enum classes can also declare members (i.e. properties and functions). A semicolon (;) must be placed between the last enum object and the first member declaration. If a member is abstract, the enum objects must implement it. enum class Color { RED { override val rgb: Int = 0xFF0000 ...

enum class Color { RED, GREEN, BLUE } Each enum constant is an object. Enum constants are separated with commas.

The following method computes the value of num raised to the power of exp using recursion: public long power(final int num, final int exp) { if (exp == 0) { return 1; } if (exp == 1) { return num; } return num * power(num, exp - 1); } This illustrates ...

You can create a UIColor from a hexadecimal number or string, e.g. 0xff00cc, "#FFFFFF" Swift Int Value extension UIColor { convenience init(hex: Int, alpha: CGFloat = 1.0) { let r = CGFloat((hex >> 16) & 0xff) / 255 let g = CGFloat((hex >> 08) &amp...

Validates value as float, and converts to float on success. var_dump(filter_var(1, FILTER_VALIDATE_FLOAT)); var_dump(filter_var(1.0, FILTER_VALIDATE_FLOAT)); var_dump(filter_var(1.0000, FILTER_VALIDATE_FLOAT)); var_dump(filter_var(1.00001, FILTER_VALIDATE_FLOAT)); var_dump(filter_var('1', FILTE...

There may be situations where you have setup a pool of MySQL connections, but you have a number of queries you would like to run in sequence: SELECT 1; SELECT 2; You could just run then using pool.query as seen elsewhere, however if you only have one free connection in the pool you must wait un...

var a:Number=0.123456789; trace(a); // 0.123456789 trace(a.toPrecision(4)); // 0.1235 trace(a.toFixed(4)); // 0.1235 trace(a.toExponential(4)); // 1.2345e-1 trace(a.toString(16)); // 0 - works for integer part only var b:Number=12345678.9876543; // a bigg...

You can use the Substring method to get any number of characters from a string at any given location. However, if you only want a single character, you can use the string indexer to get a single character at any given index like you do with an array: string s = "hello"; char c = s[1]; //...

Public Module Usage Public Sub LikeThis() Dim iCount As Integer Dim sCount As String iCount = 245 sCount = iCount.PadLeft(4, "0") Console.WriteLine(sCount) Console.ReadKey() End Sub End Module Public Module Padding <Extension> Pub...

[^0-9a-zA-Z] This will match all characters that are neither numbers nor letters (alphanumerical characters). If the underscore character _ is also to be negated, the expression can be shortened to: [^\w] Or: \W In the following sentences: Hi, what's up? I can't wait for 2017!...

NSString *testString = @"There are 42 sheep and 8672 cows."; NSError *error = nil; NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"(\\d+)" options:NSRegularExpressionCaseIns...

Problem # models.py: class Library(models.Model): name = models.CharField(max_length=100) books = models.ManyToManyField(Book) class Book(models.Model): title = models.CharField(max_length=100) # views.py def myview(request): # Query the database. libraries = Librar...

Problem Django querysets are evaluated in a lazy fashion. For example: # models.py: class Author(models.Model): name = models.CharField(max_length=100) class Book(models.Model): author = models.ForeignKey(Author, related_name='books') title = models.CharField(max_length=100) ...

Extension methods are useful for adding functionality to enumerations. One common use is to implement a conversion method. public enum YesNo { Yes, No, } public static class EnumExtentions { public static bool ToBool(this YesNo yn) { return yn == YesNo.Yes; ...

We start off with $db, an instance of the PDO class. After executing a query we often want to determine the number of rows that have been affected by it. The rowCount() method of the PDOStatement will work nicely: $query = $db->query("DELETE FROM table WHERE name = 'John'"); $count = ...

In normal mode, we can increment the nearest number on the line at or after the cursor with <C-a> and decrement it with <C-x>. In the following examples, the cursor position is indicated by ^. Incrementing and decrementing numbers for i in range(11): ^ <C-x> decrements ...