Tutorial by Examples: u

A for loop iterates over a sequence, so altering this sequence inside the loop could lead to unexpected results (especially when adding or removing elements): alist = [0, 1, 2] for index, value in enumerate(alist): alist.pop(index) print(alist) # Out: [1] Note: list.pop() is being used t...

A class can have only one constructor, that is a method called initialize. The method is automatically invoked when a new instance of the class is created. class Customer def initialize(name) @name = name.capitalize end end sarah = Customer.new('sarah') sarah.name #=> 'Sarah' ...

There is a problem when using optional arguments with a mutable default type (described in Defining a function with optional arguments), which can potentially lead to unexpected behaviour. Explanation This problem arises because a function's default arguments are initialised once, at the point whe...

Python 2.x2.3 raw_input will wait for the user to enter text and then return the result as a string. foo = raw_input("Put a message here that asks the user for input") In the above example foo will store whatever input the user provides. Python 3.x3.0 input will wait for the user ...

Python 3.x3.0 In Python 3, print functionality is in the form of a function: print("This string will be displayed in the output") # This string will be displayed in the output print("You can print \n escape characters too.") # You can print escape characters too. Pyth...

def input_number(msg, err_msg=None): while True: try: return float(raw_input(msg)) except ValueError: if err_msg is not None: print(err_msg) def input_number(msg, err_msg=None): while True: try: return ...

Python 2.x2.3 In Python 2.x, to continue a line with print, end the print statement with a comma. It will automatically add a space. print "Hello,", print "World!" # Hello, World! Python 3.x3.0 In Python 3.x, the print function has an optional end parameter that is what...

The preferred method of file i/o is to use the with keyword. This will ensure the file handle is closed once the reading or writing has been completed. with open('myfile.txt') as in_file: content = in_file.read() print(content) or, to handle closing the file manually, you can forgo with...

if (navigator.geolocation) { navigator.geolocation.getCurrentPosition(geolocationSuccess, geolocationFailure); } else { console.log("Geolocation is not supported by this browser."); } // Function that will be called if the query succeeds var geolocationSuccess = function(pos) {...

This a Basic example for using the MVVM model in a windows desktop application, using WPF and C#. The example code implements a simple "user info" dialog. The View The XAML <Grid> <Grid.ColumnDefinitions> <ColumnDefinition Width="Auto"/> ...

You can upvote (or downvote, if you want...) examples you created. Although you won't get any reputation for doing so, upvoting your the example will influence the examples' ordering on the page. Any previous contributors to the examples will get reputation. On the other hand, you might consider ...

Overview Checkboxes and radio buttons are written with the HTML tag <input>, and their behavior is defined in the HTML specification. The simplest checkbox or radio button is an <input> element with a type attribute of checkbox or radio, respectively: <input type="checkbox&quo...

Python's str type also has a method for replacing occurences of one sub-string with another sub-string in a given string. For more demanding cases, one can use re.sub. str.replace(old, new[, count]): str.replace takes two arguments old and new containing the old sub-string which is to be replace...

window.setTimout() returns a TimeoutID, which can be used to stop that timeout from running. To do this, store the return value of window.setTimeout() in a variable and call clearTimeout() with that variable as the only argument: function waitFunc(){ console.log("This will not be logged a...

The <select> element generates a drop-down menu from which the user can choose an option. <select name=""> <option value="1">One</option> <option value="2">Two</option> <option value="3">Three</option> ...

In the following example - Database for an auto shop business, we have a list of departments, employees, customers and customer cars. We are using foreign keys to create relationships between the various tables. Live example: SQL fiddle Relationships between tables Each Department may have 0 ...

A generator function is created with a function* declaration. When it is called, its body is not immediately executed. Instead, it returns a generator object, which can be used to "step through" the function's execution. A yield expression inside the function body defines a point at which...

Copying an array will copy all of the items inside the original array. Changing the new array will not change the original array. var originalArray = ["Swift", "is", "great!"] var newArray = originalArray newArray[2] = "awesome!" //originalArray = ["...

The following examples will use this array to demonstrate accessing values var exampleArray:[Int] = [1,2,3,4,5] //exampleArray = [1, 2, 3, 4, 5] To access a value at a known index use the following syntax: let exampleOne = exampleArray[2] //exampleOne = 3 Note: The value at index two is th...

It is possible to send a value to the generator by passing it to the next() method. function* summer() { let sum = 0, value; while (true) { // receive sent value value = yield; if (value === null) break; // aggregate values sum += value; ...