Tutorial by Examples: f

Consider a simple asynchronous method: async Task Foo() { Bar(); await Baz(); Qux(); } Simplifying, we can say that this code actually means the following: Task Foo() { Bar(); Task t = Baz(); var context = SynchronizationContext.Current; t.ContinueWith(task...

An Odd-Even Sort or brick sort is a simple sorting algorithm, which is developed for use on parallel processors with local interconnection. It works by comparing all odd/even indexed pairs of adjacent elements in the list and, if a pair is in the wrong order the elements are switched. The next step ...

this can also be cv-qualified, the same as any other pointer. However, due to the this parameter not being listed in the parameter list, special syntax is required for this; the cv-qualifiers are listed after the parameter list, but before the function's body. struct ThisCVQ { void no_qualifi...

C++11 Similarly to this cv-qualifiers, we can also apply ref-qualifiers to *this. Ref-qualifiers are used to choose between normal and rvalue reference semantics, allowing the compiler to use either copy or move semantics depending on which are more appropriate, and are applied to *this instead of...

This is a porting of set up sourced from DigitalOcean's tutorial of How To Serve Flask Applications with uWSGI and Nginx on Ubuntu 14.04 and some useful git resources for nginx servers. Flask Application This tutorial assume you use Ubuntu. locate var/www/ folder. Create your web app folder m...

First off, let's assume this is your initial model, inside an application called discography: from django.db import models class Album(models.Model): name = models.CharField(max_length=255) artist = models.CharField(max_length=255) Now, you realize that you want to use a ForeignKey ...

You could describe variable affectation in different ways. Typed int a = 1 int a := 1 let int a = 1 int a <- 1 No type a = 1 a := 1 let a = 1 a <- 1

As long as the function name, return statement and parameters are clear, you're fine. def incr n return n + 1 or let incr(n) = n + 1 or function incr (n) return n + 1 are all quite clear, so you may use them. Try not to be ambiguous with a variable affectation

By utilizing the pre_save we can determine if a save action on our database was about updating an existing object or creating a new one. In order to achieve this you can check the state of the model object: @receiver(pre_save, sender=User) def pre_save_user(sender, instance, **kwargs): ...

In C, all arguments are passed to functions by value, including structs. For small structs, this is a good thing as it means there is no overhead from accessing the data through a pointer. However, it also makes it very easy to accidentally pass a huge struct resulting in poor performance, particula...

// initialize library $this->load->library('form_validation'); $this->form_validation->set_rules('username', 'Username', 'required|max_length[20]'); // Add validation rules for require and max $this->form_validation->set_rules('password', 'Password', 'required|matches[passw...

Different countries have different number formats and considering this we can have different formats using Locale of java. Using locale can help in formatting Locale locale = new Locale("en", "IN"); NumberFormat numberFormat = NumberFormat.getInstance(locale); using above fo...

(defun sum-list-integers (list) (reduce '+ list)) ; 10 (sum-list-integers '(1 2 3 4)) ; 55 (sum-list-integers '(1 2 3 4 5 6 7 8 9 10))

The members of a union share the same space in memory. This means that writing to one member overwrites the data in all other members and that reading from one member results in the same data as reading from all other members. However, because union members can have differing types and sizes, the da...

DECLARE @ID AS INT; SET @ID = (SELECT MIN(ID) from TABLE); WHILE @ID IS NOT NULL BEGIN PRINT @ID; SET @ID = (SELECT MIN(ID) FROM TABLE WHERE ID > @ID); END

Catalan numbers algorithm is Dynamic Programming algorithm. In combinatorial mathematics, the Catalan numbers form a sequence of natural numbers that occur in various counting problems, often involving recursively-defined objects. The Catalan numbers on nonnegative integers n are a set of numbers t...

A palindrome is a word that can be read both ways, like 'kayak'. This example will show how to find if a given word is a palindrome using Python3. First, we need to turn a string into a stack (we will use arrays as stacks). str = "string" stk = [c for c in str] #this makes an array: [&...

To retrieve information about dplyr package and its functions' descriptions: help(package = "dplyr") No need to load the package first.

To get the list of functions within package dplyr, we first must load the package: library(dplyr) ls("package:dplyr")

You can COPY table and paste it into a file. postgres=# select * from my_table; c1 | c2 | c3 ----+----+---- 1 | 1 | 1 2 | 2 | 2 3 | 3 | 3 4 | 4 | 4 5 | 5 | (5 rows) postgres=# copy my_table to '/home/postgres/my_table.txt' using delimiters '|' with null as 'null_s...