Tutorial by Examples: if

if #available(iOS 9, *) { // iOS 9 } else { // iOS 8 or earlier }

Int("123") // Returns 123 of Int type Int("abcd") // Returns nil Int("10") // Returns 10 of Int type Int("10", radix: 2) // Returns 2 of Int type Double("1.5") // Returns 1.5 of Double type Double("abcd") // Returns nil Note that do...

git diff HEAD^ HEAD This will show the changes between the previous commit and the current commit.

Using an incorrect format specifier in the first argument to printf invokes undefined behavior. For example, the code below invokes undefined behavior: long z = 'B'; printf("%c\n", z); Here is another example printf("%f\n",0); Above line of code is undefined behavior. %...

In the following examples, we'll be using the following samples: List<Product> Products = new List<Product>() { new Product() { ProductId = 1, Name = "Book nr 1", Price = 25 }, new Product() { ProductId = 2, Name = "Book nr 2&quot...

INotifyPropertyChanged is an interface used by binding sources (i.e. the DataContext) to let the user interface or other components know that a property has been changed. WPF automatically updates the UI for you when it sees the PropertyChanged event raised. It is desirable to have this interface im...

You can diff UTF-16 encoded files (localization strings file os iOS and macOS are examples) by specifying how git should diff these files. Add the following to your ~/.gitconfig file. [diff "utf16"] textconv = "iconv -f utf-16 -t utf-8" iconv is a program to convert differe...

composer update composer update will update our dependencies as they are specified in composer.json. For example, if our project uses this configuration: "require": { "laravelcollective/html": "2.0.*" } Supposing we have actually installed the 2.0.1 version ...

This example show how you can check if a service already exists (i.e., is installed on the machine) or not. This code requires only the lowest privileges necessary, so each process can perform the check, no matter what level of security it is running at. #define UNICODE #define _UNICODE #include ...

You can select elements with different selectors : by tag : "div" by class : ".class" by id : "#id" by attribute : "[color=blue]" multiple selectors (OR): "div1, div2, class1" multiple selectors (AND): "div1 div2 class1"

The case modifier causes the Scala compiler to automatically generate common boilerplate code for the class. Implementing this code manually is tedious and a source of errors. The following case class definition: case class Person(name: String, age: Int) ... will have the following code automati...

In oracle, the difference (in days and/or fractions thereof) between two DATEs can be found using subtraction: SELECT DATE '2016-03-23' - DATE '2015-12-25' AS difference FROM DUAL; Outputs the number of days between the two dates: DIFFERENCE ---------- 89 And: SELECT TO_DATE( '201...

The semantics for this are similar to that of default value substitution, but instead of substituting a default value, it errors out with the provided error message. The forms are ${VARNAME?ERRMSG} and ${VARNAME:?ERRMSG}. The form with : will error our if the variable is unset or empty, whereas the ...

1. URLByDeletingPathExtension: If the receiver represents the root path, this property contains a copy of the original URL. If the URL has multiple path extensions, only the last one is removed. 2. URLByAppendingPathExtension: Returns a new URL made by appending a path extension to the original U...

DefaultIfEmpty is used to return a Default Element if the Sequence contains no elements. This Element can be the Default of the Type or a user defined instance of that Type. Example: var chars = new List<string>() { "a", "b", "c", "d" }; chars.Defaul...

$(window).load() was deprecated in jQuery version 1.8 (and completely removed from jQuery 3.0) and as such should not be used anymore. The reasons for the deprecation are noted on the jQuery page about this event Caveats of the load event when used with images A common challenge developers attem...

Asynchronously var fs = require('fs'); fs.stat('path/to/file', function(err) { if (!err) { console.log('file or directory exists'); } else if (err.code === 'ENOENT') { console.log('file or directory does not exist'); } }); Synchronously here, we must wr...

Callback-based: db.notification.email.find({subject: 'promisify callback'}, (error, result) => { if (error) { console.log(error); } // normal code here }); This uses bluebird's promisifyAll method to promisify what is conventionally callback-based code like above. blueb...

These functions are very similar in behaviour. The difference is that ng-if removes elements from the DOM. If there are large parts of the code that will not be shown, then ng-if is the way to go. ng-show will only hide the elements but will keep all the handlers. ng-if The ngIf directive removes ...

The if statement in the example above allows to execute a code fragment, when the condition is met. When you want to execute a code fragment, when the condition is not met you extend the if with an else. if ($a > $b) { echo "a is greater than b"; } else { echo "a is NOT gre...