Tutorial by Examples: in

Subroutines hold code. Unless specified otherwise, they are globally defined. # Functions do not (have to) specify their argument list sub returns_one { # Functions return the value of the last expression by default # The return keyword here is unnecessary, but helps readability. return 1...

using System.Text.RegularExpressions; string pattern = ":(.*?):"; string lookup = "--:text in here:--"; // Instanciate your regex object and pass a pattern to it Regex rgxLookup = new Regex(pattern, RegexOptions.Singleline, TimeSpan.FromSeconds(1)); // Get the match from y...

class Product(models.Model): name = models.CharField(max_length=20) price = models.FloatField() To Get average price of all products: >>> from django.db.models import Avg, Max, Min, Sum >>> Product.objects.all().aggregate(Avg('price')) # {'price__avg': 124.0} To ...

Subtracting the values of two pointers to an object results in a signed integer *1. So it would be printed using at least the d conversion specifier. To make sure there is a type being wide enough to hold such a "pointer-difference", since C99 <stddef.h> defines the type ptrdiff_t. ...

Most performance tips are very dependent of the current state of JS engines and are expected to be only relevant at a given time. The fundamental law of performance optimization is that you must first measure before trying to optimize, and measure again after a presumed optimization. To measure cod...

The package's official wiki has some essential materials: As a new user, you will want to check out the vignettes, FAQ and cheat sheet. Before asking a question -- here on StackOverflow or anywhere else -- please read the support page. For help on individual functions, the syntax is h...

Go to application/model File name - Home_model.php Inside the file class Home_model extends CI_Model { public $variable; public function __construct() { parent::__construct(); } public function get_data() { $query = $this->db->get('tabl...

Syntax - $this->load->model('model_name'); Practice - $this->load->model('home_model'); If you would like your model assigned to a different object name you can specify it via the second parameter of the loading method: Syntax - $this->load->model('model_name', 'foobar'); ...

Syntax $this->load->model('model_name'); $this->model_name->method_name(); Practice $this->load->model('home_model'); $this->home_model->get_data();

Syntax $array = array( '' => , ); # can pass array $singelData = ''; # something just a filed value $this->load->model('model_name'); $this->model_name->method_name($singelData, $array); Practice $array = array( 'name' => 'codeigniter', 'version' =&g...

public function method_name($single, $array) { echo $single; print_r($array); } Beware with the order which pass from controller to model.

Python makes it extremely intuitive to check if a string contains a given substring. Just use the in operator: >>> "foo" in "foo.baz.bar" True Note: testing an empty string will always result in True: >>> "" in "test" True

Javascript engines first look for variables within the local scope before extending their search to larger scopes. If the variable is an indexed value in an array, or an attribute in an associative array, it will first look for the parent array before it finds the contents. This has implications wh...

Open index.ios.js or index.android.js and delete everything between the <View> </View>. After that, write <Text> Hello World! </Text> and run the emulator. You should see Hello World! written on the screen! Congrats! You've successfully written your first Hello World!

The CustomEvent API allows developers to create custom events and trigger them on DOM nodes, passing data along the way. event = new CustomEvent(typeArg, customEventInit); typeArg - DOMString representing the name of the event. customEventInit - is optional parameters (that will be passed as e ...

# example data DT = as.data.table(mtcars, keep.rownames = TRUE) Editing a column Use the := operator inside j to create new columns or modify existing ones: DT[, mpg_sq := mpg^2] Editing on a subset of rows Use the i argument to subset to rows "where" edits should be made: DT[1:...

It is generally not considered 'best practice' to re-purpose the reserved names of Properties or Methods as the name(s) of your own procedures and variables. Bad Form - While the following is (strictly speaking) legal, working code the re-purposing of the Find method as well as the Row, Column and ...

This sample annotation indicates that the following method is deprecated. @deprecated def anUnusedLegacyMethod(someArg: Any) = { ... } This can also be equivalently written as: @deprecated def anUnusedLegacyMethod(someArg: Any) = { ... }

# example data DT <- data.table(Titanic) Suppose that, for each sex, we want the rows with the highest survival numbers: DT[Survived == "Yes", .SD[ N == max(N) ], by=Sex] # Class Sex Age Survived N # 1: Crew Male Adult Yes 192 # 2: 1st Female Adult Yes...

# example data DT = data.table(iris) DT[, Bin := cut(Sepal.Length, c(4,6,8))] Using .N .N in j stores the number of rows in a subset. When exploring data, .N is handy to... count rows in a group, DT[Species == "setosa", .N] # 50 or count rows in all groups, DT[, .N,...