Tutorial by Examples: d

Setting encoding with open() When opening a text file, you may specify it's encoding explicitly with a three-argument open(). This en-/decoder attached to a file handle is called an "I/O layer": my $filename = '/path/to/file'; open my $fh, '<:encoding(utf-8)', $filename or die "...

The utf8 pragma indicates that the source code will be interpreted as UTF-8. Of course, this will only work if your text editor is also saving the source as UTF-8 encoded. Now, string literals can contain arbitrary Unicode characters; identifiers can also contain Unicode but only word-like characte...

If we need to parse a large file, e.g. a CSV more than 10 Mbytes containing millions of rows, some use file or file_get_contents functions and end up with hitting memory_limit setting with Allowed memory size of XXXXX bytes exhausted error. Consider the following source (top-1m.csv has exactly...

After successfully installing Xamarin as described in the first example, it's time to launch the first sample application. Step 1: Creating a new Project. In Visual Studio, choose New -> Project -> Visual C# -> Cross-Platform -> Blank App (Xamarin.Forms Portable) Name the app "He...

The Salesforce application consists of several products which can be integrated with each other: Sales Cloud Marketing Page, Salesforce Documentation Service Cloud Marketing Page, Salesforce Documentation, Trailhead Marketing Cloud Marketing Page Community Cloud Marketing Page, Salesforce Do...

LeakCanary is an Open Source Java library to detect memory leaks in your debug builds. Just add the dependencies in the build.gradle: dependencies { debugCompile 'com.squareup.leakcanary:leakcanary-android:1.5.1' releaseCompile 'com.squareup.leakcanary:leakcanary-android-no-op:1.5.1' ...

static and templates folder in the apps may should also contain a folder with the name of app ex. blog this is a convention used to prevent namespace pollution, so we reference the files like /blog/base.html rather than /base.html which provides more clarity about the file we are referencing and pre...

The coordinate systems of Matplotlib come very handy when trying to annotate the plots you make. Sometimes you would like to position text relatively to your data, like when trying to label a specific point. Other times you would maybe like to add a text on top of the figure. This can easily be achi...

In order for a program to react to a certain signal, other than using default action, custom signal handler can be installed using sigaction. sigaction receives three arguments - signal to act on, pointer to sigaction_t structure which, if not NULL, is describing new behaviour and pointer to sigacti...

SELECT DATE('2003-12-31 01:02:03'); The output will be: 2003-12-31

Least squares is a standard approach to problems with more equations than unknowns, also known as overdetermined systems. Consider the four equations: x0 + 2 * x1 + x2 = 4 x0 + x1 + 2 * x2 = 3 2 * x0 + x1 + x2 = 5 x0 + x1 + x2 = 4 We can express this as a matrix multiplication A * x = b: A ...

When rendering a form 'by hand', it can be useful to know if there are fields left to render or not. The function isRendered() from the FormView class returns true if there are still fields left to be rendered to the template. This snippet prints <h3>Extra fields</h3> if there are fiel...

CREATE TABLE foo ( ... name CHARACTER SET utf8mb4 ... );

There are dozens of character sets with hundreds of collations. (A given collation belongs to only one character set.) See the output of SHOW COLLATION;. There are usually only 4 CHARACTER SETs that matter: ascii -- basic 7-bit codes. latin1 -- ascii, plus most characters needed for Western Eur...

When you created your own Models in a app, they still need to be registered in order to become available in the admin pages. This is done in the admin submodule. If your app was created using manage.py startapp, an admin.py file should already lay in you app module. Otherwise create it. #myapp/a...

C++ thrives on what is known as a Regular type (or at least Pseudo-Regular). A Regular type is a type that can be constructed and assigned-to and assigned-from via copy or move, can be destroyed, and can be compared equal-to. It can also be constructed from no arguments. Finally, it also has supp...

While a simple mock returns null (or defaults for primitives) to every call, it is possible to change that behaviour. Dependency mock = Mockito.mock(Dependency.class, new Answer() { @Override public Object answer(InvocationOnMock invocationOnMock) throws Throwable { ...

The following example illustrates how to use CullingGroups to get notifications according to the distance reference point. This script has been simplified for brevity and uses several performance heavy methods. using UnityEngine; using System.Linq; public class CullingGroupBehaviour : Mono...

You can add bounding distances on top of culling point radius. They are in a manner additional trigger conditions outside the culling points' main radius, like "close", "far" or "very far". cullingGroup.SetBoundingDistances(new float[] { 0f, 10f, 100f}); Bounding ...

As a developer, you frequently find yourself dealing with strings that are not created by your own code. These will often be supplied by third party libraries, external systems, or even end users. Validating strings of unclear provenance is considered to be one of the hallmarks of defensive program...