Tutorial by Examples: b

Math library functions that return NaN

Generally, Math functions that are given non-numeric arguments will return NaN. Math.floor("a") The square root of a negative number returns NaN, because Math.sqrt does not support imaginary or complex numbers. Math.sqrt(-1)

Blocks as Method Parameters

- (void)methodWithBlock:(returnType (^)(paramType1, paramType2, ...))name;

Comparing Objects

In order to compare the equality of custom classes, you can override == and != by defining __eq__ and __ne__ methods. You can also override __lt__ (<), __le__ (<=), __gt__ (>), and __ge__ (>). Note that you only need to override two comparison methods, and Python can handle the rest (== ...

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...

Nested output buffers

You can nest output buffers and fetch the level for them to provide different content using the ob_get_level() function. <?php $i = 1; $output = null; while( $i <= 5 ) { // Each loop, creates a new output buffering `level` ob_start(); print "Current nest level: &quo...

Capturing the output buffer to re-use later

In this example, we have an array containing some data. We capture the output buffer in $items_li_html and use it twice in the page. <?php // Start capturing the output ob_start(); $items = ['Home', 'Blog', 'FAQ', 'Contact']; foreach($items as $item): // Note we're about to step &q...

Running output buffer before any content

ob_start(); $user_count = 0; foreach( $users as $user ) { if( $user['access'] != 7 ) { continue; } ?> <li class="users user-<?php echo $user['id']; ?>"> <a href="<?php echo $user['link']; ?>"> <?php echo $user...

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: £15,000</h2> ... </body> </html> <?php...

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...

Basics of multithreading

Using the threading module, a new thread of execution may be started by creating a new threading.Thread and assigning it a function to execute: import threading def foo(): print "Hello threading!" my_thread = threading.Thread(target=foo) The target parameter references the fun...

Bold

Bold text can be created by surrounding text with either double asterisks or double underscores: **Bolded text** __Also bolded text__ Result: Bolded text Also bolded text

General Pattern that does most commonly asked about tasks

The following is how to properly use the java.util.Scanner class to interactively read user input from System.in correctly( sometimes referred to as stdin, especially in C, C++ and other languages as well as in Unix and Linux). It idiomatically demonstrates the most common things that are requested ...

Getting the First Page in Ruby

This Ruby example uses Mechanize, a library to automate web interactions. client_id is an OAuth client_id. game is the game directory to list. require 'mechanize' master_agent = Mechanize.new client_id = "123" game = "Minecraft" url = "https://api.twitch.tv/kraken...

Numbered lists

1. Lists 2. Can be 3. Numbered Lists Can be Numbered Note that the numbers themselves are ignored: 1. This is the first item 5. This is the fifth item 7. This is the seventh item This is the first item This is the fifth item This is the seventh item However, the firs...

Basic Formatting

Every format type is related to an HTML tag. The First Heading refers to the <h1> tag and is visualized like: Hello World and it's written underlining the text with =: Hello World =========== or by prepending # to the text: # Hello World The Second Heading refers to the <h2&gt...

JavaScript/Web SDK

For JavaScript, here is the code we recommend for generating, persisting and retrieving a UUID. This could be wrapped in a function can called directly from the PUBNUB.init function rather than the two step inline solution below. // get/create/store UUID var UUID = PUBNUB.db.get('session') || (fun...

Array subscript operator

You can even overload the array subscript operator []. You should always (99.98% of the time) implement 2 versions, a const and a not-const version, because if the object is const, it should not be able to modify the object returned by []. The arguments are passed by const& instead of by value...

Bitwise NOT operator

Overloading the bitwise NOT (~) is fairly simple. Scroll down for explanation Overloading outside of class/struct: T operator~(T lhs) { //Do operation return lhs; } Overloading inside of class/struct: T operator~() { T t(*this); //Do operation return t; } Note...

Bit shift operators for I/O

The operators << and >> are commonly used as "write" and "read" operators: std::ostream overloads << to write variables to the underlying stream (example: std::cout) std::istream overloads >> to read from the underlying stream to a variable (example: s...

A basic date output

Using the following code with the format string yyyy/MM/dd hh:mm.ss, we will receive the following output 2016/04/19 11:45.36 // define the format to use String formatString = "yyyy/MM/dd hh:mm.ss"; // get a current date object Date date = Calendar.getInstance().getTime(); //...

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