Tutorial by Examples: nd

To detect the endian of the device var isLittleEndian = true; (()=>{ var buf = new ArrayBuffer(4); var buf8 = new Uint8ClampedArray(buf); var data = new Uint32Array(buf); data[0] = 0x0F000000; if(buf8[0] === 0x0f){ isLittleEndian = false; } })(); Lit...

db.people.createIndex({name: 1, age: -1}) This creates an index on multiple fields, in this case on the name and age fields. It will be ascending in name and descending in age. In this type of index, the sort order is relevant, because it will determine whether the index can support a sort opera...

The NVIDIA installation guide ends with running the sample programs to verify your installation of the CUDA Toolkit, but doesn't explicitly state how. First check all the prerequisites. Check the default CUDA directory for the sample programs. If it is not present, it can be downloaded from the offi...

To show and hide a FloatingActionButton with the default animation, just call the methods show() and hide(). It's good practice to keep a FloatingActionButton in the Activity layout instead of putting it in a Fragment, this allows the default animations to work when showing and hiding. Here is an ...

:g/Hello/d Will delete every line containing the text "Hello". Important note: This is not the normal mode command d, this is the ex command :d. You can use the global command to apply normal mode keystrokes instead of ex commands by prepending normal or norm to the command. For exampl...

Modify your Gemfile to include the Devise gem: gem 'devise' Then update your gems with: $ bundle install Run the installers in your project: $ rails generate devise:install Then create your Devise model (e.g. User) with: $ rails generate devise User you'll need to set up the default ...

For Facebook config.omniauth :facebook, facebook_app_id, facebook_secret_key, :display => "popup", :scope => 'email,publish_actions', info_fields: 'email,name' For Twitter config.omniauth :twitter, twitter_app_id, twitter_secret_key, :display => "popup", :scope =&gt...

If you don't want to use SQL server you can use Amazon's hosted Dynamo DB nosql database as a session store. You'll need the AWS SDK. To install this from the Visual Studio nuget package manager console use the following command Install-Package AWSSDK You can then configure your sessionState p...

1. Print the Hadoop version hadoop version 2. List the contents of the root directory in HDFS hadoop fs -ls / 3. Report the amount of space used and available on currently mounted filesystem hadoop fs -df hdfs:/ 4. Count the number of directories,files and bytes under the paths tha...

A common problem in code that uses multidimensional arrays, arrays of pointers, etc. is the fact that Type** and Type[M][N] are fundamentally different types: #include <stdio.h> void print_strings(char **strings, size_t n) { size_t i; for (i = 0; i < n; i++) puts(str...

To start the process: $ forever start index.js warn: --minUptime not set. Defaulting to: 1000ms warn: --spinSleepTime not set. Your script will exit if it does not stay up for at least 1000ms info: Forever processing file: index.js List running Forever instances: $ forever list i...

In Python 2, True, False and None are built-in constants. Which means it's possible to reassign them. Python 2.x2.0 True, False = False, True True # False False # True You can't do this with None since Python 2.4. Python 2.x2.4 None = None # SyntaxError: cannot assign to None In ...

Remember to npm install all the files into devDependencies first. E.g. npm install --save-dev gulp gulp-concat gulp-rename gulp-uglify gulp-uglifycss Gulpfile.js var gulp = require('gulp'); var gulp_concat = require('gulp-concat'); var gulp_rename = require('gulp-rename'); var gulp_uglify = ...

To create a parallel collection from a sequential collection, call the par method. To create a sequential collection from a parallel collection, call the seq method. This example shows how you turn a regular Vector into a ParVector, and then back again: scala> val vect = (1 to 5).toVector vect:...

When using async queries, you can execute multiple queries at the same time, but not on the same context. If the execution time of one query is 10s, the time for the bad example will be 20s, while the time for the good example will be 10s. Bad Example IEnumerable<TResult1> result1; IEnumera...

Indentation level is four spaces. Only space characters may be used for indentation. No tabs. Empty lines must not be indented. (This is implied by the no trailing white space rule.) case lines should be indented with four spaces, and statements within the case should be indented with another f...

return flag ? "yes" : "no"; String cmp = (flag1 != flag2) ? "not equal" : "equal"; // Don't do this return (flag ? "yes" : "no"); Redundant grouping parentheses (i.e. parentheses that does not affect evaluation) may be used if t...

These operators have the usual precedence in C++: AND before OR. // You can drive with a foreign license for up to 60 days bool can_drive = has_domestic_license || has_foreign_license && num_days <= 60; This code is equivalent to the following: // You can drive with a foreign licens...

A condition variable is a primitive used in conjunction with a mutex to orchestrate communication between threads. While it is neither the exclusive or most efficient way to accomplish this, it can be among the simplest to those familiar with the pattern. One waits on a std::condition_variable with...

Passing a pointer argument to a T* parameter, if possible, is better than passing it to a const T* parameter. struct Base {}; struct Derived : Base {}; void f(Base* pb); void f(const Base* pb); void f(const Derived* pd); void f(bool b); Base b; f(&b); // f(Base*) is better than f(const...