Tutorial by Examples: en

In Python 2, range function returns a list while xrange creates a special xrange object, which is an immutable sequence, which unlike other built-in sequence types, doesn't support slicing and has neither index nor count methods: Python 2.x2.3 print(range(1, 10)) # Out: [1, 2, 3, 4, 5, 6, 7, 8, 9...

With any variadic function, the function must know how to interpret the variable arguments list. With the printf() or scanf() functions, the format string tells the function what to expect. The simplest technique is to pass an explicit count of the other arguments (which are normally all the same ...

As long as the element is a block, and it has an explicitly set width value, margins can be used to center block elements on a page horizontally. We add a width value that is lower than the width of the window and the auto property of margin then distributes the remaining space to the left and the ...

In your Visual Studio open the Solution Explorer window then right click on your project then choose Manage NuGet Packages from the menu: In the window that opens type EntityFramework in the search box in the top right. Or if you are using Visual Studio 2015 you'll see something like this: ...

The static (compile-time) type is used rather than the dynamic (run-time type) to match parameters. public class Base { public virtual string GetName() { return "Base"; } } public class Derived : Base { public override string GetName() { ...

Prefer public class Order { public OrderLine AddOrderLine(OrderLine orderLine) { if (orderLine == null) throw new ArgumentNullException(nameof(orderLine)); ... } } Over public class Order { public OrderLine AddOrderLine(OrderLine orderLine) { ...

NSString has a length property to get the number of characters. NSString *string = @"example"; NSUInteger length = string.length; // length equals 7 As in the Splitting Example, keep in mind that NSString uses UTF-16 to represent characters. The length is actually just the numbe...

interface IFoo { } class Foo : IFoo { } class Bar : IFoo { } var item0 = new Foo(); var item1 = new Foo(); var item2 = new Bar(); var item3 = new Bar(); var collection = new IFoo[] { item0, item1, item2, item3 }; Using OfType var foos = collection.OfType<Foo>(); // result: IEnum...

The checked out file will overwrite not yet commited changes you did in this file. This command will check out the file file.example (which is located in the directory path/to/) and overwrite any changes you might have made to this file. git checkout some-branch path/to/file some-branch can be ...

The % wildcard appended to the beginning or end (or both) of a string will allow 0 or more of any character before the beginning or after the end of the pattern to match. Using '%' in the middle will allow 0 or more characters between the two parts of the pattern to match. We are going to use this...

When working with multi-module projects, it is helpful to centralize dependencies in a single location rather than having them spread across many build files, especially for common libraries such as the Android support libraries and the Firebase libraries. One recommended way is to separate the Gra...

First, some terminology: argument (actual parameter): the actual variable being passed to a function; parameter (formal parameter): the receiving variable that is used in a function. In Python, arguments are passed by assignment (as opposed to other languages, where arguments can be passed by...

In Haskell, it often makes sense not to bother with file handles at all, but simply read or write an entire file straight from disk to memory†, and do all the partitioning/processing of the text with the pure string data structure. This avoids mixing IO and program logic, which can greatly help avoi...

virtualenv is a tool to build isolated Python environments. This program creates a folder which contains all the necessary executables to use the packages that a Python project would need. Installing the virtualenv tool This is only required once. The virtualenv program may be available through yo...

public class DatabaseHelper extends SQLiteOpenHelper { private static final String DATABASE_NAME = "Example.db"; private static final int DATABASE_VERSION = 3; // For all Primary Keys _id should be used as column name public static final String COLUMN_ID = "_id&q...

If you've got a session which you wish to destroy, you can do this with session_destroy() /* Let us assume that our session looks like this: Array([firstname] => Jon, [id] => 123) We first need to start our session: */ session_start(); /* We can now remove all the v...

Once your virtual environment has been activated, any package that you install will now be installed in the virtualenv & not globally. Hence, new packages can be without needing root privileges. To verify that the packages are being installed into the virtualenv run the following command to che...

Assuming python and python3 are both installed, it is possible to create a virtual environment for Python 3 even if python3 is not the default Python: virtualenv -p python3 foo or virtualenv --python=python3 foo or python3 -m venv foo or pyvenv foo Actually you can create virtual ...

Getting ("a", 1) ^. _1 -- returns "a" ("a", 1) ^. _2 -- returns 1 Setting ("a", 1) & _1 .~ "b" -- returns ("b", 1) Modifying ("a", 1) & _2 %~ (+1) -- returns ("a", 2) both Traversal (1, 2) & bot...

Simple record {-# LANGUAGE TemplateHaskell #-} import Control.Lens data Point = Point { _x :: Float, _y :: Float } makeLenses ''Point Lenses x and y are created. let p = Point 5.0 6.0 p ^. x -- returns 5.0 set x 10 p -- returns Point { _x = 10.0, _y = 6.0 } p & x +~ ...