Tutorial by Examples: io

Sometimes, if an action should be bind to a collection view's cell selection, you have to implement the UICollectionViewDelegate protocol. Let's say the collection view is inside a UIViewController MyViewController. Objective-C In your MyViewController.h declares that it implements the UICollecti...

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context Context is important if you ship your class for others to use.Context lets your class observer verify that its you observer which is being called. The ...

Name-based virtual hosting on Apache is described on the Apache website as such: With name-based virtual hosting, the server relies on the client to report the hostname as part of the HTTP headers. Using this technique, many different hosts can share the same IP address. Therefore, more than...

Create a file named '.jshintrc' in the root of your app, where package.json is. *Note on windows: create a file named "jshintrc.txt". Then rename it to ".jshintrc." (notice the dot at the end). This is a configuration file. It can for example tell jshint to ignore certain varia...

Node Version Manager (nvm) greatly simplifies the management of Node.js versions, their installation, and removes the need for sudo when dealing with packages (e.g. npm install ...). Fish Shell (fish) "is a smart and user-friendly command line shell for OS X, Linux, and the rest of the family&...

Every Windows Phone project contains App.cs class: public sealed partial class App : Application This class is your global application context. General Application class usage: App entry point, particularly for various activation contracts. Application lifecycle management. Application g...

Perl supports many kinds of conditional statements (statements that are based on boolean results). The most common conditional statements are if-else, unless, and ternary statements. given statements are introduced as a switch-like construct from C-derived languages and are available in versions Per...

In most scripting languages, if a function call fails, it may throw an exception and stop execution of the program. Bash commands do not have exceptions, but they do have exit codes. A non-zero exit code signals failure, however, a non-zero exit code will not stop execution of the program. This can...

The behaviour of virtual functions in constructors and destructors is often confusing when first encountered. #include <iostream> using namespace std; class base { public: base() { f("base constructor"); } ~base() { f("base destructor"); } virtual co...

Detailed instructions on getting database-design set up or installed.

Principal Component Analysis finds sequences of linear combinations of the features. The first linear combination maximizes the variance of the features (subject to a unit constraint). Each of the following linear combinations maximizes the variance of the features in the subspace orthogonal to that...

Security is a very general, broad field, and touches every aspect of development, deployment, support, among other areas. Per the (ISC)2, there are 10 domains, and include Physical security, in addition to the "Software" aspects. The intent of information security is to protect the confid...

Learning the parameters of a prediction function and testing it on the same data is a methodological mistake: a model that would just repeat the labels of the samples that it has just seen would have a perfect score but would fail to predict anything useful on yet-unseen data. This situation is call...

Detailed instructions on getting gis set up or installed.

The addition and multiplication have equivalents in this type algebra. They correspond to the tagged unions and product types. data Sum a b = A a | B b data Prod a b = Prod a b We can see how the number of inhabitants of every type corresponds to the operations of the algebra. Equivalently, we...

Functions can be seen as exponentials in our algebra. As we can see, if we take a type a with n instances and a type b with m instances, the type a -> b will have m to the power of n instances. As an example, Bool -> Bool is isomorphic to (Bool,Bool), as 2*2 = 2². iso1 :: (Bool -> Bool) -...

Usage Sometimes, you could have to debug code in another PhpStorm project, you have to update the configuration. PHP configuration In php.ini, edit file and put xdebug.remote_autostart = 1 PhpStorm configuration You also have to configure your IDE: In the phpStorm configuration, Max. sim...

The most important consequence of the One Definition Rule is that non-inline functions with external linkage should only be defined once in a program, although they can be declared multiple times. Therefore, such functions should not be defined in headers, since a header can be included multiple tim...

A function template can be overloaded under the rules for non-template function overloading (same name, but different parameter types) and in addition to that, the overloading is valid if The return type is different, or The template parameter list is different, except for the naming of paramete...

Whereas inside a Translation Unit, order of initialization of global variables is specified, order of initialization across Translation Units is unspecified. So program with following files foo.cpp #include <iostream> int dummyFoo = ((std::cout << "foo"), 0); b...