Tutorial by Examples: pt

Instances of std::weak_ptr can point to objects owned by instances of std::shared_ptr while only becoming temporary owners themselves. This means that weak pointers do not alter the object's reference count and therefore do not prevent an object's deletion if all of the object's shared pointers are ...

To get started with the jQuery UI library, you'll need to add the jQuery script, the jQuery UI script, and the jQuery UI stylesheet to your HTML. First, download jQuery UI; choose the features you need on the download page. Unzip your download, and put jquery-ui.css and jquery-ui.js (and jquery.js)...

To offset text either upward or downward you can use the tags <sup> and <sub>. To create superscript: <sup>superscript here</sup> To create subscript: <sub>subscript here</sub>

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...

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...

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...

If you specify the variable's name in the capture list, the lambda will capture it by value. This means that the generated closure type for the lambda stores a copy of the variable. This also requires that the variable's type be copy-constructible: int a = 0; [a]() { return a; // Ok, 'a' ...

With Stream Controller add-on enabled, you can use Channel Groups to subscribe to a 1000's of channels from a single client. You do this by creating a channel group and adding channels to the channel group. We'll assume pubnub variable has been initialized properly with your keys. Create a generic ...

C++14 Lambdas can capture expressions, rather than just variables. This permits lambdas to store move-only types: auto p = std::make_unique<T>(...); auto lamb = [p = std::move(p)]() //Overrides capture-by-value of `p`. { p->SomeFunc(); }; This moves the outer p variable into th...

If you precede a local variable's name with an &, then the variable will be captured by reference. Conceptually, this means that the lambda's closure type will have a reference variable, initialized as a reference to the corresponding variable from outside of the lambda's scope. Any use of the v...

By default, local variables that are not explicitly specified in the capture list, cannot be accessed from within the lambda body. However, it is possible to implicitly capture variables named by the lambda body: int a = 1; int b = 2; // Default capture by value [=]() { return a + b; }; // OK;...

In this tutorial we're going to learn how to set up the PayPal Android SDK to process a simple payment via either a PayPal payment or a credit card purchase. At the end of this example, you should have a simple button in an application that, when clicked, will forward the user to PayPal to confirm a...

C++11 A std::unique_ptr is a class template that manages the lifetime of a dynamically stored object. Unlike for std::shared_ptr, the dynamic object is owned by only one instance of a std::unique_ptr at any time, // Creates a dynamic int with value of 20 owned by a unique pointer std::unique_pt...

JSONObject and JSONArray have a few methods that are very useful while dealing with a possibility that a value your are trying to get does not exist or is of another type. JSONObject obj = new JSONObject(); obj.putString("foo", "bar"); // For existing properties of the corre...

In this example, we can use GROUP BY not only determined the sort of the rows returned, but also what rows are returned, since we're using TOP to limit the result set. Let's say we want to return the top 5 highest reputation users from an unnamed popular Q&A site. Without ORDER BY This query ...

var options = $( "#accordion" ).accordion( "option" ); This will return a PlainObject giving all the options representing the selected accordion. This will contain all the values of the keys that are explained in the Parameters section. This method takes parameters which are ...

InterruptedException is a confusing beast - it shows up in seemingly innocuous methods like Thread.sleep(), but handling it incorrectly leads to hard-to-manage code that behaves poorly in concurrent environments. At its most basic, if an InterruptedException is caught it means someone, somewhere, c...

Simply use the javascript: protocol to run the text as JavaScript instead of opening it as a normal link: <a href="javascript:myFunction();">Run Code</a> You can also achieve the same thing using the onclick attribute: <a href="#" onclick="myFunction(); r...

A group is a section of a regular expression enclosed in parentheses (). This is commonly called "sub-expression" and serves two purposes: It makes the sub-expression atomic, i.e. it will either match, fail or repeat as a whole. The portion of text it matched is accessible in the remai...

Since Groups are "numbered" some engines also support matching what a group has previously matched again. Assuming you wanted to match something where two equals strings of length three are divided by a $ you'd use: (.{3})\$\1 This would match any of the following strings: "abc$...