Tutorial by Examples: u

std::async is also able to make threads. Compared to std::thread it is considered less powerful but easier to use when you just want to run a function asynchronously. Asynchronously calling a function #include <future> #include <iostream> unsigned int square(unsigned int i){ r...

When you want to return a value from a method, you put the type you want to return in the first set of parentheses. - (NSString)returnHello { return @"Hello World"; } The value you want to return goes after the return keyword;

A Broadcast receiver is an Android component which allows you to register for system or application events. A receiver can be registered via the AndroidManifest.xml file or dynamically via the Context.registerReceiver() method. public class MyReceiver extends BroadcastReceiver { @Override ...

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Unlike C++ in C# you can call a virtual method from class constructor (OK, you can also in C++ but behavior at first is surprising). For example: abstract class Base { protected Base() { _obj = CreateAnother(); } protected virtual AnotherBase CreateAnother() { ...

To add a method to a button, first create an action method: Objective-C -(void)someButtonAction:(id)sender { // sender is the object that was tapped, in this case its the button. NSLog(@"Button is tapped"); } Swift func someButtonAction() { print("Button is tapped...

You can easily transform every component in a clickable button using the MouseArea component. The code below displays a 360x360 window with a button and a text in the center; pressing the button will change the text: import QtQuick 2.0 Rectangle { width: 360 height: 360 Rectang...

Subclass UINavigationController and then override these methods: In Objective-C: - (UIStatusBarStyle)preferredStatusBarStyle { return UIStatusBarStyleLightContent; } In Swift: override func preferredStatusBarStyle() -> UIStatusBarStyle { return .lightContent } Alternativel...

Note that you cannot overload a function based on its return type. For example: // WRONG CODE std::string getValue() { return "hello"; } int getValue() { return 0; } int x = getValue(); This will cause a compilation error as the compiler will not be able to work out wh...

It is also possible to write a context manager using generator syntax thanks to the contextlib.contextmanager decorator: import contextlib @contextlib.contextmanager def context_manager(num): print('Enter') yield num + 1 print('Exit') with context_manager(2) as cm: # the ...

To move data you first insert it into the target, then delete whatever you inserted from the source table. This is not a normal SQL operation but it may be enlightening What did you insert? Normally in databases you need to have one or more columns that you can use to uniquely identify rows so we w...

You can use the CONVERT function to cast a datetime datatype to a formatted string. SELECT GETDATE() AS [Result] -- 2016-07-21 07:56:10.927 You can also use some built-in codes to convert into a specific format. Here are the options built into SQL Server: DECLARE @convert_code INT = 100 -- See ...

@Provider public class CORSResponseFilter implements ContainerResponseFilter { public void filter( ContainerRequestContext requestContext, ContainerResponseContext responseContext ) throws IOException { MultivaluedMap<String, Object> headers = responseCo...

A Sub is a procedure that performs a specific task but does not return a specific value. Sub ProcedureName ([argument_list]) [statements] End Sub If no access modifier is specified, a procedure is Public by default. A Function is a procedure that is given data and returns a value, ideally...

A class designed to be inherited-from is called a Base class. Care should be taken with the special member functions of such a class. A class designed to be used polymorphically at run-time (through a pointer to the base class) should declare the destructor virtual. This allows the derived parts of...

When creating a recyclerview with a gridlayout layout manager you have to specify the span count in the constructor. Span count refers to the number of columns. This is fairly clunky and doesn't take into account larger screen sizes or screen orientation. One approach is to create multiple layouts f...

To add a header to a recyclerview with a gridlayout, first the adapter needs to be told that the header view is the first position - rather than the standard cell used for the content. Next, the layout manager must be told that the first position should have a span equal to the *span count of the e...

Define your class that will represent your custom error. public class ErrorDto { public int Code { get; set; } public string Message { get; set; } // other fields public override string ToString() { return JsonConvert.SerializeObject(this); } } Then put nex...

A shell script is a very versatile way to extend your build to basically anything you can think of. As an exmaple, here is a simple script to compile protobuf files and add the result java files to the source directory for further compilation: def compilePb() { exec { // NOTICE: grad...

The class we are going to test is: public class Service { private Collaborator collaborator; public Service(Collaborator collaborator) { this.collaborator = collaborator; } public String performService(String input) { return collaborator.transformStri...