Tutorial by Examples: le

Creating a table

Markdown tables are physically represented using dash - for to separate the header row from the content ones and pipe | for columns. ColumnColumnCellCell is produced by Column | Column ------ | ------ Cell | Cell You can also populate a table in any way you want - LetterDigitCharactera4...

Markdown • Tables

Creating a Variable

Declare a new variable with var, followed by a name, type, and value: var num: Int = 10 Variables can have their values changed: num = 20 // num now equals 20 Unless they're defined with let: let num: Int = 10 // num cannot change Swift infers the type of variable, so you don't always ha...

Swift Language • Variables & Properties

Local and Global Variables

Local variables are defined within a function, method, or closure: func printSomething() { let localString = "I'm local!" print(localString) } func printSomethingAgain() { print(localString) // error } Global variables are defined outside of a function, method, or c...

Swift Language • Variables & Properties

Basic usage getting content between buffers and clearing

Output buffering allows you to store any textual content (Text, HTML) in a variable and send to the browser as one piece at the end of your script. By default, php sends your content as it interprets it. <?php // Turn on output buffering ob_start(); // Print some output to the buffer (via...

PHP • Output Buffering

Using Output buffer to store contents in a file, useful for reports, invoices etc

<?php ob_start(); ?> <html> <head> <title>Example invoice</title> </head> <body> <h1>Invoice #0000</h1> <h2>Cost: &pound;15,000</h2> ... </body> </html> <?php...

PHP • Output Buffering

Using the multiprocessing module to parallelise tasks

import multiprocessing def fib(n): """computing the Fibonacci in an inefficient way was chosen to slow down the CPU.""" if n <= 2: return 1 else: return fib(n-1)+fib(n-2) p = multiprocessing.Pool() print(p.map(fib,[38,37,3...

Python Language • Parallel computation

Ignore files that have already been committed to a Git repository

If you have already added a file to your Git repository and now want to stop tracking it (so that it won't be present in future commits), you can remove it from the index: git rm --cached <file> This will remove the file from the repository and prevent further changes from being tracked by...

Git • Ignoring Files and Folders

Loading and using a module

A module can be "imported", or otherwise "required" by the require() function. For example, to load the http module that ships with Node.js, the following can be used: const http = require('http'); Aside from modules that are shipped with the runtime, you can also require mod...

Node.js • Exporting and Consuming Modules

Creating a hello-world.js module

Node provides the module.exports interface to expose functions and variables to other files. The most simple way to do so is to export only one object (function or variable), as shown in the first example. hello-world.js module.exports = function(subject) { console.log('Hello ' + subject); }...

Node.js • Exporting and Consuming Modules

Simple Category

Interface and implementation of a simple category on NSArray, named Filter, with a single method that filters numbers. It is good practice to add a prefix (PF) to the method to ensure we don't overwrite any future NSArray methods. @interface NSArray (PFFilter) - (NSArray *)pf_filterSmaller:(dou...

Objective-C Language • Categories

Implements Interface

This is an enum that is also a callable function that tests String inputs against precompiled regular expression patterns. import java.util.function.Predicate; import java.util.regex.Pattern; enum RegEx implements Predicate<String> { UPPER("[A-Z]+"), LOWER("[a-z]+&quot...

Java Language • Enums

Joining array elements in a string

To join all of an array's elements into a string, you can use the join method: console.log(["Hello", " ", "world"].join("")); // "Hello world" console.log([1, 800, 555, 1234].join("-")); // "1-800-555-1234" As you can see in ...

JavaScript • Arrays

Sourcing a file

Sourcing a file is different from execution, in that all commands are evaluated within the context of the current bash session - this means that any variables, function, or aliases defined will persist throughout your session. Create the file you wish to source sourceme.sh #!/bin/bash export A=...

Bash • Sourcing

Sample Alert

Bosun alerts are defined in the config file using a custom DSL. They use functions to evaluate time series data and will generate alerts when the warn or crit expressions are non-zero. Alerts use templates to include additional information in the notifications, which are usually an email message and...

Bosun • Getting started with Bosun

Simple Assertion

An assertion is a statement used to assert that a fact must be true when that line of code is reached. Assertions are useful for ensuring that expected conditions are met. When the condition passed to an assertion is true, there is no action. The behavior on false conditions depends on compiler fl...

C Language • Assertion

Searching for a file by name or extension

To find files/directories with a specific name, relative to pwd: $ find . -name "myFile.txt" ./myFile.txt To find files/directories with a specific extension, use a wildcard: $ find . -name "*.txt" ./myFile.txt ./myFile2.txt To find files/directories matching one of ma...

Bash • Find

Finding files by type

To find files, use the -type f flag $ find . -type f To find directories, use the -type d flag $ find . -type d To find block devices, use the -type b flag $ find /dev -type b To find symlinks, use the -type l flag $ find . -type l

Bash • Find

Executing commands against a found file

Sometimes we will need to run commands against a lot of files. This can be done using xargs. find . -type d -print | xargs -r chmod 770 The above command will recursively find all directories (-type d) relative to . (which is your current working directory), and execute chmod 770 on them. The -...

Bash • Find

Check whether a variable is of a certain qualified type

#include <stdio.h> #define is_const_int(x) _Generic((&x), \ const int *: "a const int", \ int *: "a non-const int", \ default: "of other type") int main(void) { const int i = 1; int j = 1; double...

C Language • Generic selection

Finding file by access / modification time

On an ext filesystem, each file has a stored Access, Modification, and (Status) Change time associated with it - to view this information you can use stat myFile.txt; using flags within find, we can search for files that were modified within a certain time range. To find files that have been modifi...

Bash • Find