Tutorial by Examples: ha

Dirty reads (or uncommitted reads) are reads of rows which are being modified by an open transaction. This behavior can be replicated by using 2 separate queries: one to open a transaction and write some data to a table without committing, the other to select the data to be written (but not yet com...

boost::program_options::notify can be used to report any errors in the paramters passing #include <boost/program_options.hpp> #include <string> #include <iostream> int main(int argc, char** argv) { namespace po = boost::program_options; po::variables_map vm; po::op...

When writing wrappers for unmanaged resources, you should subclass SafeHandle rather than trying to implement IDisposable and a finalizer yourself. Your SafeHandle subclass should be as small and simple as possible to minimize the chance of a handle leak. This likely means that your SafeHandle imple...

Value-type fields only C++ declaration typedef union { char c; int i; } CharOrInt; C# declaration [StructLayout(LayoutKind.Explicit)] public struct CharOrInt { [FieldOffset(0)] public byte c; [FieldOffset(0)] public int i; } Mixing value-type and reference...

An integer type large enough to represent all characters of the largest supported extended character set, also known as the wide-character set. (It is not portable to make the assumption that wchar_t uses any particular encoding, such as UTF-16.) It is normally used when you need to store character...

The method charCodeAt retrieves the Unicode character code of a single character: var charCode = "µ".charCodeAt(); // The character code of the letter µ is 181 To get the character code of a character in a string, the 0-based position of the character is passed as a parameter to charCo...

Partitioning by HASH is used primarily to ensure an even distribution of data among a predetermined number of partitions. With range or list partitioning, you must specify explicitly into which partition a given column value or set of column values is to be stored; with hash partitioning, MySQL take...

Pushing a patch applies the patch to the repository while poping a patch unapplies the patch from the repository. Pop the current patch off the queue with hg qpop and push it back onto the queue with hg qpush: hg qpop hg qpush Pop all patches: hg qpop -a PUsh all patches: hg qpush -a ...

Behat provides Gherkin Syntax which is a human-readable format. It allows you to easily describe your user stories. To start with Behat you should install it with Composer and then initialize your test files: $ composer require --dev behat/behat="^3.0.5" $ ./vendor/bin/behat --init ...

Mink provides an interface for web drivers (like Goutte and Selenium) as well as a MinkContext which, when extended, provides additional web language for our steps. To install Mink (and the default Goutte driver): $ composer require --dev behat/mink-extension="^2.0" $ composer require -...

From documentation: The HttpContext.Items collection is the best location to store data that is only needed while processing a given request. Its contents are discarded after each request. It is best used as a means of communicating between components or middleware that operate at different poi...

The predicate function matches can be used to evaluate strings on the fly without use of any object declarations. IF matches( val = 'Not a hex string' regex = '[0-9a-f]*' ). cl_demo_output=>display( 'This will not display' ). ELSEIF matches( val = '6c6f7665' reg...

The Symbol.for method allows you to register and look up global symbols by name. The first time it is called with a given key, it creates a new symbol and adds it to the registry. let a = Symbol.for('A'); The next time you call Symbol.for('A'), the same symbol will be returned instead of a new o...

.exr -1 gives you details about the last exception thrown. !analyze -v usually does a good job as well. For .NET, the command !pe of the SOS extension shows details about the .NET exception that was thrown.

array_flip function will exchange all keys with its elements. $colors = array( 'one' => 'red', 'two' => 'blue', 'three' => 'yellow', ); array_flip($colors); //will output array( 'red' => 'one', 'blue' => 'two', 'yellow' => 'three' )

In this example, a destructor is explicitly invoked for an object that will later be automatically destroyed. struct S { ~S() { std::cout << "destroying S\n"; } }; int main() { S s; s.~S(); } // UB: s destroyed a second time here A similar issue occurs when a st...

This snippet is an helper function to enumerate all files older than a specified age, it's useful - for example - when you have to delete old log files or old cached data. static IEnumerable<string> EnumerateAllFilesOlderThan( TimeSpan maximumAge, ...

Basic Error Handling By default, Express will look for an 'error' view in the /views directory to render. Simply create the 'error' view and place it in the views directory to handle errors. Errors are written with the error message, status and stack trace, for example: views/error.pug html bo...

This query returns all the documents with element "company" and its value as "marklogic" cts:element-value-query(xs:QName('company'), 'marklogic'))

Return the number of characters in the string Syntax: CHAR_LENGTH(str) CHAR_LENGTH('foobar') -- 6 CHAR_LENGTH('fööbar') -- 6 -- contrast with LENGTH(...) = 8