Tutorial by Examples: t

Generalized capture

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...

C++ • Lambdas

Capture by reference

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...

C++ • Lambdas

Default capture

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;...

C++ • Lambdas

Your First Controller

A controller is a basic structure used in Angular to preserve scope and handle certain actions within a page. Each controller is coupled with an HTML view. Below is a basic boilerplate for an Angular app: <!DOCTYPE html> <html lang="en" ng-app='MyFirstApp'> <head...

AngularJS • Controllers

Recursive setTimeout

To repeat a function indefinitely, setTimeout can be called recursively: function repeatingFunc() { console.log("It's been 5 seconds. Execute the function again."); setTimeout(repeatingFunc, 5000); } setTimeout(repeatingFunc, 5000); Unlike setInterval, this ensures that t...

JavaScript • Intervals and Timeouts

Console.WriteLine()

Dim x As Int32 = 128 Console.WriteLine(x) ' Variable ' Console.WriteLine(3) ' Integer ' Console.WriteLine(3.14159) ' Floating-point number ' Console.WriteLine("Hello, world") ' String ' Console.WriteLine(myObject) ' Outputs the value from calling myObject.ToString() The Console.Wri...

Visual Basic .NET Language • Console

Console.Write()

Dim x As Int32 = 128 Console.Write(x) ' Variable ' Console.Write(3) ' Integer ' Console.Write(3.14159) ' Floating-point number ' Console.Write("Hello, world") ' String ' The Console.Write() method is identical to the Console.WriteLine() method except that it prints the given argumen...

Visual Basic .NET Language • Console

Creating a backup of a database or table

Create a snapshot of a whole database: mysqldump [options] db_name > filename.sql Create a snapshot of multiple databases: mysqldump [options] --databases db_name1 db_name2 ... > filename.sql mysqldump [options] --all-databases > filename.sql Create a snapshot of one or more tables...

MySQL • Backup using mysqldump

Restoring a backup of a database or table

mysql [options] db_name < filename.sql Note that: db_name needs to be an existing database; your authenticated user has sufficient privileges to execute all the commands inside your filename.sql; The file extension .sql is fully a matter of style. Any extension would work. You cannot spe...

MySQL • Backup using mysqldump

Conversion to function pointer

If a lambda's capture list is empty, then the lambda has an implicit conversion to a function pointer that takes the same arguments and returns the same return type: auto sorter = [](int lhs, int rhs) -> bool {return lhs < rhs;}; using func_ptr = bool(*)(int, int); func_ptr sorter_func = ...

C++ • Lambdas

High-resolution timestamps

performance.now() returns a precise timestamp: The number of milliseconds, including microseconds, since the current web page started to load. More generally, it returns the time elapsed since the performanceTiming.navigationStart event. t = performance.now(); For example, in a web browser's ma...

JavaScript • Timestamps

Low-resolution timestamps

Date.now() returns the number of whole milliseconds that have elapsed since 1 January 1970 00:00:00 UTC. t = Date.now(); For example, Date.now() returns 1461069314 if it was called on 19 April 2016 at 12:35:14 GMT.

JavaScript • Timestamps

Support for legacy browsers

In older browsers where Date.now() is unavailable, use (new Date()).getTime() instead: t = (new Date()).getTime(); Or, to provide a Date.now() function for use in older browsers, use this polyfill: if (!Date.now) { Date.now = function now() { return new Date().getTime(); }; }

JavaScript • Timestamps

Getting API credentials

To authenticate to Watson services, you need credentials for each service that you plan to use. Depending on the service, you will need to pass a username and password with Basic Authentication, or you will need to pass an API key in a parameter for each request you make. How to get credentials for...

ibm-watson-cognitive • Getting started with ibm-watson-cognitive

Android: Accepting a PayPal / Credit Card Payment

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...

PayPal • Mobile PayPal / Credit Card Payments

Unique ownership (std::unique_ptr)

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...

C++ • Smart Pointers

Encoding data as JSON

If you need to create a JSONObject and put data in it, consider the following example: // Create a new javax.json.JSONObject instance. JSONObject first = new JSONObject(); first.put("foo", "bar"); first.put("temperature", 21.5); first.put("year", 2016);...

Java Language • JSON in Java

Decoding JSON data

If you need to get data from a JSONObject, consider the following example: String json = "{\"foo\":\"bar\",\"temperature\":21.5,\"year\":2016,\"message\":{\"Hello\":\"world\"},\"months\":[\"January\",\&qu...

Java Language • JSON in Java

optXXX vs getXXX methods

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...

Java Language • JSON in Java

Attribute Selectors

Overview Attribute selectors can be used with various types of operators that change the selection criteria accordingly. They select an element using the presence of a given attribute or attribute value. Selector(1)Matched elementSelects elements...CSS Version[attr]<div attr>With attribute a...

CSS • Selectors