Tutorial by Examples: f

Almost any MPI call returns an integer error code, which signifies the success of the operation. If no error occurs, the return code is MPI_SUCCESS: if (MPI_Some_op(...) != MPI_SUCCESS) { // Process error } If an error occurs, MPI calls an error handler associated with the communicator, ...

A function is similar in look to a mixin but it doesn't add any styles, it only returns a value. Functions should be used to prevent repeated logic in your styles. Sass has some built-in functions that are called using the standard CSS function syntax. h1 { background: hsl(0, 25%, 50%); } ...

To make a module eligible for Hot Module Replacement (HMR), the simplest way is to add module.hot.accept() inside the module, like this: // ... if(module.hot) { module.hot.accept(); // This will make current module replaceable }

To create a redistributable package (e.g. a ZIP archive or setup program), it's usually enough to simply invoke CPack using a syntax very similar to calling CMake: cpack path/to/build/directory Depending on the environment this will gather all required/installed files for the project and put the...

It is easy to get confused in the C preprocessor, and treat it as part of C itself, but that is a mistake because the preprocessor is just a text substitution mechanism. For example, if you write /* WRONG */ #define MAX 100; int arr[MAX]; the code expands to int arr[100;]; which is a synta...

You can define central config info's in a separate gradle include file Centralizing dependencies via "dependencies.gradle" file a stand alone properties file Versioning your builds via "version.properties" file or do it with root gradle.properties file the project structu...

Obfuscation is often considered as a magic solution for code protection, by making your code harder to understand if it ever gets de-compiled by hackers. But if you're thinking that removing the Log.x(..) actually removes the information the hackers need, you'll have a nasty surprise. Removing al...

In some circumstances (for example obtaining a Google API key) you need to find your keystore fingerprint. Gradle has a convenient task that display all the signing information, including keystore fingerprints: ./gradlew signingReport This is a sample output: :app:signingReport Variant: releas...

Enums contains only constants and can be compared directly with ==. So, only reference check is needed, no need to use .equals method. Moreover, if .equals used incorrectly, may raise the NullPointerException while that's not the case with == check. enum Day { GOOD, AVERAGE, WORST; } publi...

The Standard (10.4) states: Member functions can be called from a constructor (or destructor) of an abstract class; the effect of making a virtual call (10.3) to a pure virtual function directly or indirectly for the object being created (or destroyed) from such a constructor (or destructor) is u...

An array containing the full version information split into elements, much more convenient than $BASH_VERSION if you're just looking for the major version: ~> $ for ((i=0; i<=5; i++)); do echo "BASH_VERSINFO[$i] = ${BASH_VERSINFO[$i]}"; done BASH_VERSINFO[0] = 3 BASH_VERSINFO[1] =...

To get the name of the current function - type: my_function() { echo "This function is $FUNCNAME" # This will output "This function is my_function" } This instruction will return nothing if you type it outside the function: my_function echo "This function i...

Contains the Internal Field Separator string that bash uses to split strings when looping etc. The default is the white space characters: \n (newline), \t (tab) and space. Changing this to something else allows you to split strings using different characters: IFS="," INPUTSTR="a,b,c...

LINQ provides a built-in function for checking the equality of two IEnumerables, and that function can be used on arrays. The SequenceEqual function will return true if the arrays have the same length and the values in corresponding indices are equal, and false otherwise. int[] arr1 = { 3, 5, 7 };...

Consider this example function to check if a host is up: is_alive() { ping -c1 "$1" &> /dev/null } This function sends a single ping to the host specified by the first function parameter. The output and error output of ping are both redirected to /dev/null, so the functi...

Decorator is one of structural design patterns. It is used to add, remove or change behaviour of object. This document will teach you how to use Decorator DP properly. Let me explain the idea of it to you on a simple example. Imagine you're now in Starbobs, famous coffee company. You can place an o...

Things you need A paid Apple Developer Program Membership A valid App ID and identifier for you app (like com.example.MyApp) which is not used before anywhere Access to developer.apple.com and Member Center An iOS Device to test (as Push Notifications don't work on Simulator) Enabling t...

You can find description of the driver here. The quick example is: import psycopg2 db_host = 'postgres.server.com' db_port = '5432' db_un = 'user' db_pw = 'password' db_name = 'testdb' conn = psycopg2.connect("dbname={} host={} user={} password={}".format( ...

An extremely simple tool for installing PostgreSQL on a Mac is available by downloading Postgres.app. You can change preferences to have PostgreSQL run in the background or only when the application is running.

foo = "bar" foo[0] = "c" # Error Immutable variable value can not be changed once they are created.