Tutorial by Examples: s

A common statement is if !(some condition). Ruby offers the alternative of the unless statement. The structure is exactly the same as an if statement, except the condition is negative. Also, the unless statement does not support elsif, but it does support else: # Prints not inclusive unless 'hell...

Given a random vector v = rand(10,1); if you want the sum of its elements, do NOT use a loop s = 0; for ii = 1:10 s = s + v(ii); end but use the vectorized capability of the sum() function s = sum(v); Functions like sum(), mean(), prod() and others, have the ability to operate ...

To find a match, the regex engine will consume characters one by one. When a partial match begins, the engine will remember the start position so it can go back in case the following characters don't complete the match. If the match is complete, the is no backtracking If the match isn't complete...

The function in_array() returns true if an item exists in an array. $fruits = ['banana', 'apple']; $foo = in_array('banana', $fruits); // $foo value is true $bar = in_array('orange', $fruits); // $bar value is false You can also use the function array_search() to get the key of a specifi...

Govendor is a tool that is used to import 3rd party packages into your code repository in a way that is compatible with golang's vendoring. Say for example that you are using a 3rd party package bosun.org/slog: package main import "bosun.org/slog" func main() { slog.Infof(&quo...

A flags-style enum value needs to be tested with bitwise logic because it may not match any single value. [Flags] enum FlagsEnum { Option1 = 1, Option2 = 2, Option3 = 4, Option2And3 = Option2 | Option3; Default = Option1 | Option3, } The Default value is actually a ...

NSAttributedString (and its mutable sibling NSMutableAttributedString) allows you to create strings that are complex in their appearance to the user. A common application is to use this to display a string and adding custom kerning / letter-spacing. This would be achieved as follows (where label ...

Objective-C CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"position.x"]; animation.fromValue = @0; animation.toValue = @320; animation.duration = 1; [_label.layer addAnimation:animation forKey:@"basic"]; Swift let animation = CAB...

OBJECTIVE-C CATransition* transition = [CATransition animation]; transition.startProgress = 0; transition.endProgress = 1.0; transition.type = @"flip"; transition.subtype = @"fromLeft"; transition.duration = 0.8; transition.repeatCount = 5; [_label.layer addAnimation:tran...

Objective-C CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:@"position.x"]; animation.values = @[ @0, @10, @-10, @10, @0 ]; animation.keyTimes = @[ @0, @(1 / 6.0), @(3 / 6.0), @(5 / 6.0), @1 ]; animation.duration = 0.4; animation.additive = YES; [_label.lay...

use Data::Dumper; my $data_structure = { foo => 'bar' }; print Dumper $data_structure; Using Data::Dumper is an easy way to look at data structures or variable content at run time. It ships with Perl and you can load it easily. The Dumper function returns the data structure serialized in a...

Sometimes Data::Dumper is not enough. Got a Moose object you want to inspect? Huge numbers of the same structure? Want stuff sorted? Colored? Data::Printer is your friend. use Data::Printer; p $data_structure; Data::Printer writes to STDERR, like warn. That makes it easier to find the outpu...

The docker rmi command is used to remove images: docker rmi <image name> The full image name must be used to remove an image. Unless the image has been tagged to remove the registry name, it needs to be specified. For example: docker rmi registry.example.com/username/myAppImage:1.3.5 I...

Detailed instructions on getting emacs set up or installed. Official instructions are available on the GNU Emacs website. Debian systems On systems with the Debian package manager (such as Debian, Ubuntu, and Mint) Emacs can be installed via the simple command: sudo apt-get install emacs For ...

Tkinter comes pre-installed with the Python installer binaries for Mac OS X and the Windows platform. So if you install Python from the official binaries for Mac OS X or Windows platform, you are good to go with Tkinter. For Debian versions of Linux you have to install it manually by using the foll...

XML is made of basic building blocks, which are: element text attributes comments processing instructions An element has angle brackets: <element/> <element>some content</element> An attribute appears in an opening element tag: <element attribute-name="...

An XML document is a text file that conforms to the XML specification's well-formedness rules. Such a conforming document is said to be well-formed (not to be confused with valid). XML is very strict with well-formedness in comparison to other languages such as HTML. A text file that is not well-for...

docker run --restart=always -d <container> By default, Docker will not restart containers when the Docker daemon restarts, for example after a host system reboot. Docker provides a restart policy for your containers by supplying the --restart command line option. Supplying --restart=always ...

Const ForReading = 1 Const ForWriting = 2 Const ForAppending = 8 Sub FsoExample() Dim fso As Object ' declare variable Set fso = CreateObject("Scripting.FileSystemObject") ' Set it to be a File System Object ' now use it to check if a file exists Dim myFilePath A...

Const ForReading = 1 Const ForWriting = 2 Const ForAppending = 8 Sub ReadTextFileExample() Dim fso As Object Set fso = CreateObject("Scripting.FileSystemObject") Dim sourceFile As Object Dim myFilePath As String Dim myFileText As String myFilePath = &...