Tutorial by Examples: u

Using fflush on an input stream

The POSIX and C standards explicitly state that using fflush on an input stream is undefined behavior. The fflush is defined only for output streams. #include <stdio.h> int main() { int i; char input[4096]; scanf("%i", &i); fflush(stdin); // <-- unde...

C Language • Undefined behavior

Child Pseudo Class

"The :nth-child(an+b) CSS pseudo-class matches an element that has an+b-1 siblings before it in the document tree, for a given positive or zero value for n" - MDN :nth-child pseudo-selector12345678910:first-child✔:nth-child(3)✔:nth-child(n+3)✔✔✔✔✔✔✔✔:nth-child(3n)✔✔✔:nth-child(3n+1)...

CSS • Selectors

Raising SIGALARM with the default action

Using alarm, user can schedule SIGALARM signal to be raised after specified interval. In case user did not blocked, ignored or specified explicit signal handler for this signal, the default action for this signal will be performed on arrival. Per specification default action for SIGALARM is to termi...

POSIX • Signals

Create child process and wait until it exits

This program demonstrates how to run another process using fork() and wait its termination using waitpid(): fork() creates an identical copy of the current process. The original process is the parent process, while the newly created one is the child process. Both processes continue exactly afte...

POSIX • Processes

Using a Savitzky–Golay filter

Given a noisy signal: import numpy as np import matplotlib.pyplot as plt np.random.seed(1) x = np.linspace(0,2*np.pi,100) y = np.sin(x) + np.random.random(100) * 0.2 plt.plot(x,y) plt.show() one can smooth it using a Savitzky–Golay filter using the scipy.signal.savgol_filter() method...

scipy • Smoothing a signal

Ranges of numeric types

The ranges of the integer types are implementation-defined. The header <limits> provides the std::numeric_limits<T> template which provides the minimum and maximum values of all fundamental types. The values satisfy guarantees provided by the C standard through the <climits> and (&...

C++ • Implementation-defined behavior

Communicating with a Web Worker

Since workers run in a separate thread from the one that created them, communication needs to happen via postMessage. Note: Because of the different export prefixes, some browsers have webkitPostMessage instead of postMessage. You should override postMessage to make sure workers "work" (n...

JavaScript • Workers

Multiple non-identical definitions (the One Definition Rule)

If a class, enum, inline function, template, or member of a template has external linkage and is defined in multiple translation units, all definitions must be identical or the behavior is undefined according to the One Definition Rule (ODR). foo.h: class Foo { public: double x; private...

C++ • Undefined Behavior

External Stylesheet Use

Use the link attribute in the document's head: <head> <link rel="stylesheet" type="text/css" href="stylesheet.css"> </head> You can also use stylesheets provided from websites via a content delivery network, or CDN for short. (for example, Bo...

HTML • Using HTML with CSS

Multiple Stylesheets

It's possible to load multiple stylesheets: <head> <link rel="stylesheet" type="text/css" href="general.css"> <link rel="stylesheet" type="text/css" href="specific.css"> </head> Note that later files a...

HTML • Using HTML with CSS

Android Step 1: Layout, Initialization, and Handling Server Response

The complete sample code for this application (Android + Node server) is available in the PayPal Developer Github repository. The first stage of creating the Android portion of our application is to set up a basic layout and handle responses that come back from the server that we'll set up in Node....

PayPal • Mobile Future Payments (End to End App)

Android Step 2: Async Server Request

The complete sample code for this application (Android + Node server) is available in the PayPal Developer Github repository. At this point the PayPal future payments button has been clicked, we have an auth code and metadata ID from the PayPal SDK, and we need to pass those on to our server to com...

PayPal • Mobile Future Payments (End to End App)

Basics of Higher Order Functions

Review Partial Application before proceeding. In Haskell, a function that can take other functions as arguments or return functions is called a higher-order function. The following are all higher-order functions: map :: (a -> b) -> [a] -> [b] filter :: (a -> Bool) -> [a] ...

Haskell Language • Higher-order functions

Creating Object and setting properties using reflection

Lets say we have a class Classy that has property Propertua public class Classy { public string Propertua {get; set;} } to set Propertua using reflection: var typeOfClassy = typeof (Classy); var classy = new Classy(); var prop = typeOfClassy.GetProperty("Propertua"); prop.Se...

.NET Framework • Reflection

A doubly linked list

An example of code showing how nodes can be inserted at a doubly linked list, how the list can easily be reversed, and how it can be printed in reverse. #include <stdio.h> #include <stdlib.h> /* This data is not always stored in a structure, but it is sometimes for ease of use */ s...

C Language • Linked lists

Multiple Version Tables

For some tags it makes sense to have multiple version tables. There might be different subsets of a programming language or framework available, say for different device types as in this example. The different tables should be prefaced with a heading. This markup: ## desktop development kit ## ...

Documentation • Versions

Versions of an Example (multiple version tables)

If there are many version tables, the title of the desired one has to be included in angle brackets.  This content is for Micro Framework 4.4

Documentation • Versions

Multiple Conditionals

Multiple conditions can be used.  content

Documentation • Versions

Simple Mutex Usage

POSIX thread library provides implementation of the mutex primitive, used for the mutual exclusion. Mutex is created using pthread_mutex_init, and destroyed using pthread_mutex_destroy. Obtaining a mutex can be done using pthread_mutex_lock or pthread_mutex_trylock, (depending if the timeout is desi...

POSIX • Threads

Quotename

Returns a Unicode string surrounded by delimiters to make it a valid SQL Server delimited identifier. Parameters: character string. A string of Unicode data, up to 128 characters (sysname). If an input string is longer than 128 characters function returns null. quote character. Optional. A sing...

Microsoft SQL Server • String Functions