Tutorial by Examples: er

using System.Text; using System.IO; string filename = "c:\path\to\file.txt"; //'using' structure allows for proper disposal of stream. using (StreamWriter writer = new StreamWriter(filename")) { writer.WriteLine("Text to Write\n"); }

Comparing sets In R, a vector may contain duplicated elements: v = "A" w = c("A", "A") However, a set contains only one copy of each element. R treats a vector like a set by taking only its distinct elements, so the two vectors above are regarded as the same: set...

The %in% operator compares a vector with a set. v = "A" w = c("A", "A") w %in% v # TRUE TRUE v %in% w # TRUE Each element on the left is treated individually and tested for membership in the set associated with the vector on the right (consisting of all its...

To count how many elements of two sets overlap, one could write a custom function: xtab_set <- function(A, B){ both <- union(A, B) inA <- both %in% A inB <- both %in% B return(table(inA, inB)) } A = 1:20 B = 10:30 xtab_set(A, B) # inB ...

Imagine you have the following HTML: <div> <label>Name:</label> John Smith </div> And you need to locate the text "John Smith" after the label element. In this case, you can locate the label element by text and then use .next_sibling property: from ...

Sets are unordered collections of distinct elements. But sometimes we want to work with unordered collections of elements that are not necessarily distinct and keep track of the elements' multiplicities. Consider this example: >>> setA = {'a','b','b','c'} >>> setA set(['a', 'c'...

You can restrict the valid types used in a generic class by bounding that type in the class definition. Given the following simple type hierarchy: public abstract class Animal { public abstract String getSound(); } public class Cat extends Animal { public String getSound() { ...

Sometimes it's necessary to be able to extract values from an object using only references (ie. without transferring ownership). struct Token { pub id: u32 } struct User { pub token: Option<Token> } fn main() { // Create a user with an arbitrary token let user = User...

For if you have to fine-tune what is published. import { Mongo } from 'meteor/mongo'; import { Meteor } from 'meteor/meteor'; import { Random } from 'meteor/random'; if (Meteor.isClient) { // established this collection on the client only. // a name is required (first parameter) and this...

On the server, you can create a publication like this. this.userId is the id of the user who is currently logged in. If no user is logged in, you might want to throw an error and respond to it. import Secrets from '/imports/collections/Secrets'; Meteor.publish('protected_data', function () { ...

Swift let stackView = UIStackView() stackView.axis = .Vertical stackView.alignment = .Fill // .Leading .FirstBaseline .Center .Trailing .LastBaseline stackView.distribution = .Fill // .FillEqually .FillProportionally .EqualSpacing .EqualCentering let label = UILabel(frame: CGRectZero) label....

The boolean type cannot be cast to/from any other primitive type. A char can be cast to/from any numeric type by using the code-point mappings specified by Unicode. A char is represented in memory as an unsigned 16-bit integer value (2 bytes), so casting to byte (1 byte) will drop 8 of those bits (...

Numeric primitives can be cast in two ways. Implicit casting happens when the source type has smaller range than the target type. //Implicit casting byte byteVar = 42; short shortVar = byteVar; int intVar = shortVar; long longVar = intvar; float floatVar = longVar; double doubleVar = floatVar...

The simplest use case is using the subprocess.call function. It accepts a list as the first argument. The first item in the list should be the external application you want to call. The other items in the list are arguments that will be passed to that application. subprocess.call([r'C:\path\to\a...

In Angular $scope is the glue between the Controller and the View that helps with all of our data binding needs. Controller As is another way of binding controller and view and is mostly recommended to use. Basically these are the two controller constructs in Angular (i.e $scope and Controller As). ...

Although it is possible to create a fragment constructor with parameters, Android internally calls the zero-argument constructor when recreating fragments (for example, if they are being restored after being killed for Android's own reasons). For this reason, it is not advisable to rely on a constru...

let string1 = "Hello" //simple string let string2 = "Line\nNewLine" //string with newline escape sequence let string3 = @"Line\nSameLine" //use @ to create a verbatim string literal let string4 = @"Line""with""quoutes inside" //dou...

When trying to select from a table called order like this select * from order the error rises: Error Code: 1064. You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'order' at line 1 Reserved keywords in MySQ...

Lambda expressions can be used to handle events, which is useful when: The handler is short. The handler never needs to be unsubscribed. A good situation in which a lambda event handler might be used is given below: smtpClient.SendCompleted += (sender, args) => Console.WriteLine("Ema...

public interface IShape { decimal Area(); } public struct Rectangle : IShape { public decimal Length { get; set; } public decimal Width { get; set; } public decimal Area() { return Length * Width; } }