Tutorial by Examples: for

A lot of Vim users find the Esc too hard to reach, and end up finding another mapping that's easy to reach from the home row. Note that Ctrl-[ may be equivalent to Esc on an English keyboard, and is much easier to reach. jk inoremap jk <ESC> This one is really easy to trigger; just smash...

Pipe operators are used to pass parameters to a function in a simple and elegant way. It allows to eliminate intermediate values and make function calls easier to read. In F#, there are two pipe operators: Forward (|>): Passing parameters from left to right let print message = print...

In Swift, memory management is done for you automatically using Automatic Reference Counting. (See Memory Management) Allocation is the process of reserving a spot in memory for an object, and in Swift understanding the performance of such requires some understanding of the heap and the stack. The h...

This error occurs when tables are not adequately structured to handle the speedy lookup verification of Foreign Key (FK) requirements that the developer is mandating. CREATE TABLE `gtType` ( `type` char(2) NOT NULL, `description` varchar(1000) NOT NULL, PRIMARY KEY (`type`) ) ENGINE=InnoD...

While server side-code can run with elevated privileges, there is not an equivalent method to elevate privileges in client-side code (for obvious security reasons). As an alternative, you can specify credentials to emulate the access of a specific user or service account. To specify credentials, bu...

When testing for any of several equality comparisons: if a == 3 or b == 3 or c == 3: it is tempting to abbreviate this to if a or b or c == 3: # Wrong This is wrong; the or operator has lower precedence than ==, so the expression will be evaluated as if (a) or (b) or (c == 3):. The correct w...

Structure for Binary Search Tree (BST) nodes: struct node { int data; node * left; node * right; } Search Algorithm // Check if a value exists in the tree bool BSTSearch(node * current, int value) { if (current->data == value) { return true; } e...

help <command> This will display the Bash help (manual) page for the specified built-in. For example, help unset will show: unset: unset [-f] [-v] [-n] [name ...] Unset values and attributes of shell variables and functions. For each NAME, remove the corresponding variable or ...

SimpleDateFormatter is great in a pinch, but like the name suggests it doesn't scale well. If you hard-code "MM/dd/yyyy" all over your application your international users won't be happy. Let Java do the work for you Use the static methods in DateFormat to retrieve the right formatting ...

Install module and read docs npm i formidable@latest Example of server on 8080 port var formidable = require('formidable'), http = require('http'), util = require('util'); http.createServer(function(req, res) { if (req.url == '/upload' && req.method.toLowerCase() == 'pos...

// This iterates through a range between two DateTimes // with the given iterator (any of the Add methods) DateTime start = new DateTime(2016, 01, 01); DateTime until = new DateTime(2016, 02, 01); // NOTICE: As the add methods return a new DateTime you have // to overwrite dt in the itera...

This iterates from 4 to 13 (inclusive). for i in 4..13 puts "this is #{i}.th number" end We can also iterate over arrays using for names = ['Siva', 'Charan', 'Naresh', 'Manish'] for name in names puts name end

The MAF file format is a tab-delimited text file format intended for describing somatic DNA mutations detected in sequencing results, and is distinct from the Multiple Alignment Format file type, which is intended for representing aligned nucleotide sequences. Column headers and ordering may someti...

+ (CALayer *)gradientBGLayerForBounds:(CGRect)bounds colors:(NSArray *)colors { CAGradientLayer * gradientBG = [CAGradientLayer layer]; gradientBG.frame = bounds; gradientBG.colors = colors; return gradientBG; }

Melting: The basics Melting is used to transform data from wide to long format. Starting with a wide data set: DT = data.table(ID = letters[1:3], Age = 20:22, OB_A = 1:3, OB_B = 4:6, OB_C = 7:9) We can melt our data using the melt function in data.table. This returns another data.table in long...

Validate that an attribute's value matches a regular expression using format and the with option. class User < ApplicationRecord validates :name, format: { with: /\A\w{6,10}\z/ } end You can also define a constant and set its value to a regular expression and pass it to the with: option. ...

In order to dynamically decide what beans to inject, we can use FactoryBeans. These are classes which implement the factory method pattern, providing instances of beans for the container. They are recognized by Spring and can be used transparently, without need to know that the bean comes from a fac...

Here is a basic example form with one required text field and one submit button, which submits to a custom function: class Page_Controller extends ContentController { private static $allowed_actions = array( 'ExampleForm' ); public function ExampleForm() { $fiel...

using System; using System.Threading; using System.Threading.Tasks; class Program { static void Main( string[] args ) { object sync = new object(); int sum = 0; Parallel.For( 1, 1000, ( i ) => { lock( sync ) sum = sum + i; // lock is necessa...

Using range-base loops, you can loop over a sub-part of a given container or other range by generating a proxy object that qualifies for range-based for loops. template<class Iterator, class Sentinel=Iterator> struct range_t { Iterator b; Sentinel e; Iterator begin() const { return ...