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Using an incorrect format specifier in the first argument to printf invokes undefined behavior. For example, the code below invokes undefined behavior: long z = 'B'; printf("%c\n", z); Here is another example printf("%f\n",0); Above line of code is undefined behavior. %...

These examples assume that you already know what Java 7's NIO is in general, and you are used to writing code using java.io.File. Use these examples as a means to quickly find more NIO-centric documentation for migrating. There is much more to Java 7's NIO such as memory-mapped files or opening a Z...

instance Monoid [a] where mempty = [] mappend = (++) Checking the Monoid laws for this instance: mempty `mappend` x = x <-> [] ++ xs = xs -- prepending an empty list is a no-op x `mappend` mempty = x <-> xs ++ [] = xs -- appending an empty list is a no-op x...

mconcat :: [a] -> a is another method of the Monoid typeclass: ghci> mconcat [Sum 1, Sum 2, Sum 3] Sum {getSum = 6} ghci> mconcat ["concat", "enate"] "concatenate" Its default definition is mconcat = foldr mappend mempty.

In the following examples, we'll be using the following samples: List<Product> Products = new List<Product>() { new Product() { ProductId = 1, Name = "Book nr 1", Price = 25 }, new Product() { ProductId = 2, Name = "Book nr 2&quot...

Wikipedia currently defines a pure function as follows: The function always evaluates the same result value given the same argument value(s). The function result value cannot depend on any hidden information or state that may change while program execution proceeds or between different executions...

A common question is "I have a value of IO a, but I want to do something to that a value: how do I get access to it?" How can one operate on data that comes from the outside world (for example, incrementing a number typed by the user)? The point is that if you use a pure function on data ...

Suppose you have this type: data Person = Person { name :: String, age:: Int } deriving (Show, Eq) and two values: alex = Person { name = "Alex", age = 21 } jenny = Person { name = "Jenny", age = 36 } a new value of type Person can be created by copying from alex, specif...

import pandas as pd # Save dataframe to pickled pandas object df.to_pickle(file_name) # where to save it usually as a .plk # Load dataframe from pickled pandas object df= pd.read_pickle(file_name)

The continue keyword halts the current iteration of a loop but does not terminate the loop. Just like the break statement the continue statement is situated inside the loop body. When executed, the continue statement causes execution to immediately jump to the loop conditional. In the followin...

Find single record based on id. $model = User::findOne($id); Select single column based on id. $model = User::findOne($id)->name; Retrieve the single record from the database based on condition. $model = User::find()->one(); // give first record $model = User::find()->where(['i...

Using scenario you can perform validation on different situation Define scenario in model class class User extends \yii\db\ActiveRecord { public static function tableName() { return 'user_master'; } // define validation in rule() function public ...

Steps to Create component: Create a folder named components in your project root folder Create your component inside components folder e.g.: MyComponent.php namespace app\components; use Yii; use yii\base\Component; use yii\base\InvalidConfigException; class MyComponent ...

Create function in MyComponent.php namespace app\components; use Yii; use yii\base\Component; use yii\base\InvalidConfigException; use yii\helpers\Url; use yii\helpers\ArrayHelper; use app\models\User; class MyComponent extends Component ...

A session is usually obtained using sessionmaker, which creates a Session class unique to your application. Most commonly, the Session class is bound to an engine, allowing instances to use the engine implicitly. from sqlalchemy.orm import sessionmaker # Initial configuration arguments Session ...

New or detached objects may be added to the session using add(): session.add(obj) A sequence of objects may be added using add_all(): session.add_all([obj1, obj2, obj3]) An INSERT will be emitted to the database during the next flush, which happens automatically. Changes are persisted when t...

To delete persisted objects use delete(): session.delete(obj) Actual deletion from the database will happen on next flush.

There are many ways find the location of a value in an array. The following example snippets all assume that the array is one of the following: String[] strings = new String[] { "A", "B", "C" }; int[] ints = new int[] { 1, 2, 3, 4 }; In addition, each one sets...

Using ActiveCell or ActiveSheet can be source of mistakes if (for any reason) the code is executed in the wrong place. ActiveCell.Value = "Hello" 'will place "Hello" in the cell that is currently selected Cells(1, 1).Value = "Hello" 'will always place "Hello&...

So you've uploaded your files to a folder say /backend/web/uploads/ and you want these uploads to be visible on the frontend too. The easiest option is to create a symlink in the frontend that links to the backend: ln -s /path/to/backend/web/uploads/ /path/to/frontend/web/uploads In your views y...