Tutorial by Examples: au

Within a LOOP, you can use the Common Lisp (return) form in any expression, which will cause the LOOP form to immediately evaluate to the value given to return. LOOP also has a return clause which works almost identically, the only difference being that you don't surround it with parentheses. The c...

By default, GHCI's prompt shows all the modules you have loaded into your interactive session. If you have many modules loaded this can get long: Prelude Data.List Control.Monad> -- etc The :set prompt command changes the prompt for this interactive session. Prelude Data.List Control.Monad&g...

Equals is declared in the Object class itself. public virtual bool Equals(Object obj); By default, Equals has the following behavior: If the instance is a reference type, then Equals will return true only if the references are the same. If the instance is a value type, then Equals will...

The sum 1 + 2 + 3 + ... + n Simplifies to n(n+1) / 2. Notice that this quantity is Θ(n2). This shortcut arises frequently in the analysis of algorithms like insertion sort or selection sort. Numbers of the form n(n+1)/2 are called the triangular numbers.

The following example encrypts a given data block using AES. The encryption key is derived in a secure way (random salt, 1000 rounds of SHA-256). The encryption uses AES in CBC mode with random IV. Note that the data stored in the class EncryptedData (salt, iv, and encryptedData) can be concatenate...

Authenticate user with Plus login onCreate GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN) .requestIdToken(getString(R.string.default_web_client_id)) .requestScopes(new Scope(Scopes.PLUS_LOGIN)) .requestEmail() .build(); mGoogleApiClient...

We often encounter a situation where a property we're trying to extract doesn't exist in the object/array, resulting in a TypeError (while destructuring nested objects) or being set to undefined. While destructuring we can set a default value, which it will fallback to, in case of it not being found...

Without Auto Layout, animation is accomplished changing a view's frame over time. With Auto Layout, the constraints dictate the view frame, so you have to animate the constraints instead. This indirection makes animation harder to visualize. Here are the ways to animate with Auto Layout: Change ...

Add a key named Required background modes in property list (.plist) file .. as following picture.. And add following code in AppDelegate.h #import <AVFoundation/AVFoundation.h> #import <AudioToolbox/AudioToolbox.h> AppDelegate.m in application didFinishLaunchingWithOptions [[...

let view = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 100)) view.backgroundColor = UIColor.orange self.view.addSubview(view) UIView.animate(withDuration: 0.75, delay: 0.5, options: .curveEaseIn, animations: { //This will cause view to go from (0,0) to // (self.view.frame.origi...

SELECT * FROM customers WHERE id IN ( SELECT DISTINCT customer_id FROM orders ); The above will give you all the customers that have orders in the system.

VBA is compiled in run-time, which has a huge negative impact on it's performance, everything built-in will be faster, try to use them. As an example I'm comparing SUM and COUNTIF functions, but you can use if for anything you can solve with WorkSheetFunctions. A first attempt for those would be t...

with clause is used to combine matching clauses. It looks like we combine anonymous functions or handle function with multiple bodies (matching clauses). Consider the case: we create a user, insert it into DB, then create greet email and then send it to the user. Without the with clause we might ...

Query: SELECT * FROM Customers ORDER BY CustomerID LIMIT 3; Result: CustomerID CustomerName ContactName Address City PostalCode Country 1 Alfreds Futterkiste Maria Anders Obere Str. 57 Berlin 12209 Ge...

def foo(li=[]): li.append(1) print(li) foo([2]) # Out: [2, 1] foo([3]) # Out: [3, 1] This code behaves as expected, but what if we don't pass an argument? foo() # Out: [1] As expected... foo() # Out: [1, 1] Not as expected... This is because default arguments of function...

In order to ssh into a server your identity's public key has to be added to the list of trusted keys. Most commonly this is done per-user: ssh-copy-id -i ~/.ssh/<identity>.pub <user>@<hostname> Which can be also done manually: cat ~/.ssh/<identity>.pub | ssh <user>...

Inheritance the a fundamental mechanism of CSS by which the computed values of some properties of an element are applied to its' children. This is particularly useful when you want to set a global style to your elements rather than having to set said properties to each and every element in your mark...

This storage class denotes that an identifier has automatic storage duration. This means once the scope in which the identifier was defined ends, the object denoted by the identifier is no longer valid. Since all objects, not living in global scope or being declared static, have automatic storage d...

Imagine you are on the master branch and something is not working as expected (a regression was introduced), but you don't know where. All you know is, that is was working in the last release (which was e.g., tagged or you know the commit hash, lets take old-rel here). Git has help for you, finding...

Simple steps to use scrollview with autolayout. Create a new project with single view application Select the default viewcontroller and change its screen size to iPhone-4inch from attributes inspector. Add a scrollview to your viewcontroller's view as follows and set background color to blue ...