Tutorial by Examples: pt

Introduction: clean up temporary files

You can use the trap command to "trap" signals; this is the shell equivalent of the signal() or sigaction() call in C and most other programming languages to catch signals. One of the most common uses of trap is to clean up temporary files on both an expected and unexpected exit. Unfortu...

Bash • Using "trap" to react to signals and system events

For entire scripts

Strict mode can be applied on entire scripts by placing the statement "use strict"; before any other statements. "use strict"; // strict mode now applies for the rest of the script Strict mode is only enabled in scripts where you define "use strict". You can combin...

JavaScript • Strict mode

Exception and Error handling

try/catch try..catch blocks can be used to control the flow of a program where Exceptions may be thrown. They can be caught and handled gracefully rather than letting PHP stop when one is encountered: try { // Do a bunch of things... throw new Exception('My test exception!'); } catch (E...

PHP • Exception Handling and Error Reporting

Avoiding KeyError Exceptions

One common pitfall when using dictionaries is to access a non-existent key. This typically results in a KeyError exception mydict = {} mydict['not there'] Traceback (most recent call last): File "<stdin>", line 1, in <module> KeyError: 'not there' One way to avoid...

Python Language • Dictionary

Event Bubbling and Capturing

Events fired on DOM elements don't just affect the element they're targeting. Any of the target's ancestors in the DOM may also have a chance to react to the event. Consider the following document: <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> </hea...

DOM • Events

Uploading a file via jQuery in JavaScript

// ... file selected from a file <input> file = event.target.files[0]; $.ajax({ url: 'https://content.dropboxapi.com/2/files/upload', type: 'post', data: file, processData: false, contentType: 'application/octet-stream', headers: { "Authorization&q...

Dropbox API • Uploading a file

Uploading a file from text via jQuery in JavaScript

var data = new TextEncoder("utf-8").encode("Test"); $.ajax({ url: 'https://content.dropboxapi.com/2/files/upload', type: 'post', data: data, processData: false, contentType: 'application/octet-stream', headers: { "Authorization": ...

Dropbox API • Uploading a file

Attempting to list a non-existant folder using the SwiftyDropbox library, as an example of error handling

// List folder Dropbox.authorizedClient!.files.listFolder(path: "/nonexistantpath").response { response, error in print("*** List folder ***") if let result = response { print("Folder contents:") for entry in result.entries { pr...

Dropbox API • Listing a folder

Using For Loop to List Iterate Over Numbers

#! /bin/bash for i in {1..10}; do # {1..10} expands to "1 2 3 4 5 6 7 8 9 10" echo $i done This outputs the following: 1 2 3 4 5 6 7 8 8 10

Bash • Control Structures

Use a module map to import C headers

A module map can simply import mymodule by configuring it to read C header files and make them appear as Swift functions. Place a file named module.modulemap inside a directory named mymodule: Inside the module map file: // mymodule/module.modulemap module mymodule { header "defs.h&q...

Swift Language • Working with C and Objective-C

Parse English date descriptions into a Date format

Using the strtotime() function combined with date() you can parse different English text descriptions to dates: // Gets the current date echo date("m/d/Y", strtotime("now")), "\n"; // prints the current date echo date("m/d/Y", strtotime("10 September 2...

PHP • Working with Dates and Time

Displaying the top JavaScript questions of the month from Stack Overflow's API

We can make an AJAX request to Stack Exchange's API to retrieve a list of the top JavaScript questions for the month, then present them as a list of links. If the request fails or the returns an API error, our promise error handling displays the error instead. 6 View live results on HyperWeb. c...

JavaScript • AJAX

Create an empty data.frame

A data.frame is a special kind of list: it is rectangular. Each element (column) of the list has same length, and where each row has a "row name". Each column has its own class, but the class of one column can be different from the class of another column (unlike a matrix, where all elemen...

R Language • Data frames

Hello World message using cscript and wscript

WScript.Echo "Hello world!" This displays a message on the console if run with cscript.exe (the console host) or in a message box if run with wscript.exe (the GUI host). If you're using VBScript as the server-side scripting language for a web page (for classic ASP, for example), Respo...

vbscript • Getting started with vbscript

Step 2: Creating a Subscription for a User using a Billing Agreement (Node Sample)

The second step to creating a subscription for a user is to create and execute a billing agreement, based on an existing activated billing plan. This example assumes that you have already gone through and activated a billing plan in the previous example, and have an ID for that billing plan to refer...

PayPal • Creating Subscriptions / Recurring Payments

Step 1: Creating a Subscription Model using a Billing Plan (Node Sample)

When creating a subscription for a user, you first need to create and activate a billing plan that a user is then subscribed to using a billing agreement. The full process for creating a subscription is detailed in the remarks of this topic. Within this example, we're going to be using the PayPal N...

PayPal • Creating Subscriptions / Recurring Payments

Inviting a member to a shared folder via jQuery in JavaScript

$.ajax({ url: 'https://api.dropboxapi.com/2/sharing/add_folder_member', type: 'POST', processData: false, data: JSON.stringify({"shared_folder_id": "84528192421","members": [{"member": {".tag": "email","email":...

Dropbox API • Sharing a folder

Optional binding and "where" clauses

Optionals must be unwrapped before they can be used in most expressions. if let is an optional binding, which succeeds if the optional value was not nil: let num: Int? = 10 // or: let num: Int? = nil if let unwrappedNum = num { // num has type Int?; unwrappedNum has type Int print(&quo...

Swift Language • Conditionals

Include script tag in head of HTML page

To load jQuery from the official CDN, go to the jQuery website. You'll see a list of different versions and formats available. Now, copy the source of the version of jQuery, you want to load. Suppose, you want to load jQuery 2.X, click uncompressed or minified tag which will show you something li...

jQuery • Getting started with jQuery

Sharing ownership (std::shared_ptr)

The class template std::shared_ptr defines a shared pointer that is able to share ownership of an object with other shared pointers. This contrasts to std::unique_ptr which represents exclusive ownership. The sharing behavior is implemented through a technique known as reference counting, where the...

C++ • Smart Pointers