Tutorial by Examples: r

PHP has built in function pcntl_fork for creating child process. pcntl_fork is same as fork in unix. It does not take in any parameters and returns integer which can be used to differentiate between parent and child process. Consider the following code for explanation <?php // $pid is the P...

Interprocess communication allows programmers to communicate between different processes. For example let us consider we need to write an PHP application that can run bash commands and print the output. We will be using proc_open , which will execute the command and return a resource that we can com...

# This uses the 'sample.xml' given in the XML::Twig example. # Module requirements (1.70 and above for use of load_xml) use XML::LibXML '1.70'; # let's be a good perl dev use strict; use warnings 'all'; # Create the LibXML Document Object my $xml = XML::LibXML->new(); # Where ...

The simplest possible binary you could build Has no dependencies Takes no command line arguments Just writes "Hello world!" to stdout After you've built buildapp, you can just... $ buildapp --eval '(defun main (argv) (declare (ignore argv)) (write-line "Hello, world!"))'...

A more realistic example involves a project you're building with multiple files on disk (rather than an --eval option passed to buildapp), and some dependencies to pull in. Because arbitrary things can happen during the finding and loading of asdf systems (including loading other, potentially unrel...

Uploaded files are available in request.files, a MultiDict mapping field names to file objects. Use getlist — instead of [] or get — if multiple files were uploaded with the same field name. request.files['profile'] # single file (even if multiple were sent) request.files.getlist('charts') # li...

WTForms provides a FileField to render a file type input. It doesn't do anything special with the uploaded data. However, since Flask splits the form data (request.form) and the file data (request.files), you need to make sure to pass the correct data when creating the form. You can use a Combine...

It may be useful to have one catch-all view where you handle complex logic yourself based on the path. This example uses two rules: The first rule specifically catches / and the second rule catches arbitrary paths with the built-in path converter. The path converter matches any string (including sl...

An enumerations value in no way needs to be unique: #include <stdlib.h> /* for EXIT_SUCCESS */ #include <stdio.h> /* for printf() */ enum Dupes { Base, /* Takes 0 */ One, /* Takes Base + 1 */ Two, /* Takes One + 1 */ Negative = -1, AnotherZero /* Takes Negativ...

SQL Server 2008 R2 SET TRANSACTION ISOLATION LEVEL REPEATABLE READ This transaction isolation level is slightly less permissive than READ COMMITTED, in that shared locks are placed on all data read by each statement in the transaction and are held until the transaction completes, as opposed to b...

SQL Server 2008 R2 SET TRANSACTION ISOLATION LEVEL SERIALIZEABLE This isolation level is the most restrictive. It requests range locks the range of key values that are read by each statement in the transaction. This also means that INSERT statements from other transactions will be blocked if the...

We can create it by two way. First from database properties designer mode: And by sql scripts: USE master; GO -- Create the database with the default data -- filegroup and a log file. Specify the -- growth increment and the max size for the -- primary data file. CREATE DATABASE TestDB ON...

CROSS APPLY enables you to "join" rows from a table with dynamically generated rows returned by some table-value function. Imagine that you have a Company table with a column that contains an array of products (ProductList column), and a function that parse these values and returns a set ...

CROSS APPLY enables you to "join" rows from a table with collection of JSON objects stored in a column. Imagine that you have a Company table with a column that contains an array of products (ProductList column) formatted as JSON array. OPENJSON table value function can parse these values...

If you store a list of tags in a row as coma separated values, STRING_SPLIT function enables you to transform list of tags into a table of values. CROSS APPLY enables you to "join" values parsed by STRING_SPLIT function with a parent row. Imagine that you have a Product table with a colu...

This section describes some basic DDL (="Data Definition Language") commands to create a database, a table within a database, a view and finally a stored procedure. Create Database The following SQL command creates a new database Northwind on the current server, using pathC:\Program Fi...

Stop the MySQL (mysqld) server/daemon process. Start the MySQL server process the --skip-grant-tables option so that it will not prompt for a password: mysqld_safe --skip-grant-tables & Connect to the MySQL server as the root user: mysql -u root Change password: (5.7.6 and newer): ALT...

The -path parameter allows to specify a pattern to match the path of the result. The pattern can match also the name itself. To find only files containing log anywhere in their path (folder or name): find . -type f -path '*log*' To find only files within a folder called log (on any level): fin...

Detailed instructions on getting azure-active-directory set up or installed.

In Julia, when looping through an iterable object I is done with the for syntax: for i = I # or "for i in I" # body end Behind the scenes, this is translated to: state = start(I) while !done(I, state) (i, state) = next(I, state) # body end Therefore, if you wan...