Tutorial by Examples: v

The simplest way to create an error is by using the errors package. errors.New("this is an error") If you want to add additional information to an error, the fmt package also provides a useful error creation method: var f float64 fmt.Errorf("error with some additional informatio...

The getAll() method retrieves all values from the preferences. We can use it, for instance, to log the current content of the SharedPreferences: private static final String PREFS_FILE = "MyPrefs"; public static void logSharedPreferences(final Context context) { SharedPreferences s...

A Table View is a list of rows that can be selected. Each row is populated from a data source. This example creates a simple table view in which each row is a single line of text. Add a UITableView to your Storyboard Although there are a number of ways to create a UITableView, one of the easiest...

Sometimes you may want to start a new activity while removing previous activities from the back stack, so the back button doesn't take you back to them. One example of this might be starting an app on the Login activity, taking you through to the Main activity of your application, but on logging out...

2.2 let aString = "This is a test string." // first, reverse the String's characters let reversedCharacters = aString.characters.reverse() // then convert back to a String with the String() initializer let reversedString = String(reversedCharacters) print(reversedString) // &q...

Method 1: Below query will be applicable for SQL Server 2000+ version (Contains 12 columns) SELECT * FROM dbo.sysdatabases Method 2: Below query extract information about databases with more informations (ex: State, Isolation, recovery model etc.) Note: This is a catalog view and will be availa...

First we need to install composer. Steps to install composer Install Composer. curl -sS https://getcomposer.org/installer | php Now change directory: sudo mv composer.phar /usr/local/bin/composer Check composer working composer Now Composer installed. There two ways to install Yii2 adv...

In Python 2, print is a statement: Python 2.x2.7 print "Hello World" print # print a newline print "No newline", # add trailing comma to remove newline print >>sys.stderr, "Error" # print to stderr print("hello"...

Even just reading the value of a pointer that was freed (i.e. without trying to dereference the pointer) is undefined behavior(UB), e.g. char *p = malloc(5); free(p); if (p == NULL) /* NOTE: even without dereferencing, this may have UB */ { } Quoting ISO/IEC 9899:2011, section 6.2.4 §2: ...

The FOR XML PATH can be used for concatenating values into string. The example below concatenates values into a CSV string: DECLARE @DataSource TABLE ( [rowID] TINYINT ,[FirstName] NVARCHAR(32) ); INSERT INTO @DataSource ([rowID], [FirstName]) VALUES (1, 'Alex') ,(2, 'Peter') ...

Sometimes you want to iterate over a range of dates from a start date to some end date. You can do it using datetime library and timedelta object: import datetime # The size of each step in days day_delta = datetime.timedelta(days=1) start_date = datetime.date.today() end_date = start_date ...

Python 2.x2.7 In Python 2 there are two variants of string: those made of bytes with type (str) and those made of text with type (unicode). In Python 2, an object of type str is always a byte sequence, but is commonly used for both text and binary data. A string literal is interpreted as a byte s...

The standard division symbol (/) operates differently in Python 3 and Python 2 when applied to integers. When dividing an integer by another integer in Python 3, the division operation x / y represents a true division (uses __truediv__ method) and produces a floating point result. Meanwhile, the ...

Ruby on Rails provides a model generator you can use to create ActiveRecord models. Simply use rails generate model and provide the model name. $ rails g model user In addition to the model file in app/models, the generator will also create: the Test in test/models/user_test.rb the Fixtures ...

Step 1: Open a Workbook Step 2 Option A: Press Alt + F11 This is the standard shortcut to open the VBE. Step 2 Option B: Developer Tab --> View Code First, the Developer Tab must be added to the ribbon. Go to File -> Options -> Customize Ribbon, then check the box for developer. ...

A custom component that takes the type of a component as input and creates an instance of that component type inside itself. When the input is updated, the previously added dynamic component is removed and the new one added instead. @Component({ selector: 'dcl-wrapper', template: `<div #...

Few people have issue regarding error message not displaying if existing value is being entered in textbox. So, For Example I'm not allowing user to enter existing email. signup.php (Page where you wanted to sign up new user without existing email id) Remove use yii\bootstrap\ActiveForm; (if p...

You can iterate over arrays either by using enhanced for loop (aka foreach) or by using array indices: int[] array = new int[10]; // using indices: read and write for (int i = 0; i < array.length; i++) { array[i] = i; } Java SE 5 // extended for: read only for (int e : array) { ...

Some people have issues regarding error messages not being displayed if an existing value is being entered. For example I'm not allowing a user signup with an existing email. View <?php ...................... <?= $form->field($modelUser, 'email')->textInput(['class'=&gt...

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 ...