Tutorial by Examples: en

Slices have both length and capacity. The length of a slice is the number of elements currently in the slice, while the capacity is the number of elements the slice can hold before needing to be reallocated. When creating a slice using the built-in make() function, you can specify its length, and ...

if condition: body The if statements checks the condition. If it evaluates to True, it executes the body of the if statement. If it evaluates to False, it skips the body. if True: print "It is true!" >> It is true! if False: print "This won't get printed.....

if condition: body else: body The else statement will execute it's body only if preceding conditional statements all evaluate to False. if True: print "It is true!" else: print "This won't get printed.." # Output: It is true! if False: print &...

To catch a long click and use it you need to provide appropriate listener to button: View.OnLongClickListener listener = new View.OnLongClickListener() { public boolean onLongClick(View v) { Button clickedButton = (Button) v; String buttonText = clickedButton.getText().toStri...

It's a bad idea to hard code paths in your application. One should always use relative urls so that your code can work seamlessly across different machines. The best way to set this up is to define a variable like this import os BASE_DIR = os.path.dirname(os.path.dirname(__file__)) Then use th...

Using environment variables is a widely used way to setting an app's config depending on it environment, as stated in The Twelve-Factor App. As configurations are likely to change between deployment environments, this is a very interesting way to modify the configuration without having to dig in th...

public enum DayOfWeek { Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday } // Enum to string string thursday = DayOfWeek.Thursday.ToString(); // "Thursday" string seventhDay = Enum.GetName(typeof(DayOfWeek), 6); // "Satur...

As Array conforms to SequenceType, we can use map(_:) to transform an array of A into an array of B using a closure of type (A) throws -> B. For example, we could use it to transform an array of Ints into an array of Strings like so: let numbers = [1, 2, 3, 4, 5] let words = numbers.map { Stri...

The things Array contains values of Any type. let things: [Any] = [1, "Hello", 2, true, false, "World", 3] We can extract values of a given type and create a new Array of that specific type. Let's say we want to extract all the Int(s) and put them into an Int Array in a safe ...

ThenBy can only be used after a OrderBy clause allowing to order using multiple criteria var persons = new[] { new {Id = 1, Name = "Foo", Order = 1}, new {Id = 1, Name = "FooTwo", Order = 2}, new {Id = 2, Name = "Bar", Order = 2}, new {Id = 2, Nam...

In (standard ANSI/ISO) SQL, the operator for string concatenation is ||. This syntax is supported by all major databases except SQL Server: SELECT 'Hello' || 'World' || '!'; --returns HelloWorld! Many databases support a CONCAT function to join strings: SELECT CONCAT('Hello', 'World'); --retur...

SQL Server The LEN doesn't count the trailing space. SELECT LEN('Hello') -- returns 5 SELECT LEN('Hello '); -- returns 5 The DATALENGTH counts the trailing space. SELECT DATALENGTH('Hello') -- returns 5 SELECT DATALENGTH('Hello '); -- returns 6 It should be noted though, that DATALE...

Type information does not need to be included in the cases of a discriminated union. By omitting type information you can create a union that simply represents a set of choices, similar to an enum. // This union can represent any one day of the week but none of // them are tied to a specific unde...

To apply a function to every item in an array, use array_map(). This will return a new array. $array = array(1,2,3,4,5); //each array item is iterated over and gets stored in the function parameter. $newArray = array_map(function($item) { return $item + 1; }, $array); $newArray now is a...

You can access the elements of an array by their indices. Array index numbering starts at 0. %w(a b c)[0] # => 'a' %w(a b c)[1] # => 'b' You can crop an array using range %w(a b c d)[1..2] # => ['b', 'c'] (indices from 1 to 2, including the 2) %w(a b c d)[1...2] # => ['b'] (indic...

Creating a new migration file with the correct filename every time you need to change your schema would be a chore. Thankfully, Laravel's artisan command can generate the migration for you: php artisan make:migration add_last_logged_in_to_users_table You can also use the --table and --create fla...

Run-length encoding captures the lengths of runs of consecutive elements in a vector. Consider an example vector: dat <- c(1, 2, 2, 2, 3, 1, 4, 4, 1, 1) The rle function extracts each run and its length: r <- rle(dat) r # Run Length Encoding # lengths: int [1:6] 1 3 1 1 2 2 # valu...

The virtualenvwrapper utility simplifies working with virtual environments and is especially useful if you are dealing with many virtual environments/projects. Instead of having to deal with the virtual environment directories yourself, virtualenvwrapper manages them for you, by storing all virtual...

MKLocalSearch allows users to search for location using natural language strings like "gym". Once the search get completed, the class returns a list of locations within a specified region that match the search string. Search results are in form of MKMapItem within MKLocalSearchResponse ob...

The filter or map functions should often be replaced by list comprehensions. Guido Van Rossum describes this well in an open letter in 2005: filter(P, S) is almost always written clearer as [x for x in S if P(x)], and this has the huge advantage that the most common usages involve predicates tha...