Tutorial by Examples: ed

When using the DllImport attribute you have to know the correct dll and method name at compile time. If you want to be more flexible and decide at runtime which dll and methods to load, you can use the Windows API methods LoadLibrary(), GetProcAddress() and FreeLibrary(). This can be helpful if the ...

Name-based virtual hosting on Apache is described on the Apache website as such: With name-based virtual hosting, the server relies on the client to report the hostname as part of the HTTP headers. Using this technique, many different hosts can share the same IP address. Therefore, more than...

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In some places in Common Lisp, a series of forms are evaluated in order. For instance, in the body of a defun or lambda, or the body of a dotimes. In those cases, writing multiple forms in order works as expected. In a few places, however, such as the then and else parts of an if expressions, onl...

You can use npm install -g to install a package "globally." This is typically done to install an executable that you can add to your path to run. For example: npm install -g gulp-cli If you update your path, you can call gulp directly. On many OSes, npm install -g will attempt to writ...

The following batch file will popup a UAC Prompt allowing you to accept elevated Administrator privileges for the batch session. Add your tasks code to :usercode section of the batch, so they run with elevated privileges. @echo off setlocal EnableDelayedExpansion :: test and acquire admin rights ...

In most scripting languages, if a function call fails, it may throw an exception and stop execution of the program. Bash commands do not have exceptions, but they do have exit codes. A non-zero exit code signals failure, however, a non-zero exit code will not stop execution of the program. This can...

Principal Component Analysis finds sequences of linear combinations of the features. The first linear combination maximizes the variance of the features (subject to a unit constraint). Each of the following linear combinations maximizes the variance of the features in the subspace orthogonal to that...

Redis configuration: Install redis (2.4+ required) Install phpredis Install the Magento extension Cm_Cache_Backend_Redis (only for Magento 1.7 and below) Edit your app/etc/local.xml: <global> ... <cache> <backend>Cm_Cache_Backend_Redis</backend> <b...

The most important consequence of the One Definition Rule is that non-inline functions with external linkage should only be defined once in a program, although they can be declared multiple times. Therefore, such functions should not be defined in headers, since a header can be included multiple tim...

A typed hole is a single underscore (_) or a valid Haskell identifier which is not in scope, in an expression context. Before the existance of typed holes, both of these things would trigger an error, so the new syntax does not interfere with any old syntax. Controlling behaviour of typed holes Th...

The value of a type hole can simply said to be undefined, although a typed hole triggers a compile-time error, so it is not strictly necessary to assign it a value. However, a typed hole (when they are enabled) produces a compile time error (or warning with deferred type errors) which states the nam...

In this question, @Viclib asked about using rewrite rules to exploit typeclass laws to eliminate some overloaded function calls: Mind the following class: class ListIsomorphic l where toList :: l a -> [a] fromList :: [a] -> l a I also demand that toList . fromList == id. H...

The div is a block-level element, i.e it occupies the whole of the page width and the siblings are place one below the other irrespective of their width. <div> <p>This is DIV 1</p> </div> <div> <p>This is DIV 2</p> </div> The output of...

To create seeders, you may use the make:seeder Artisan command. All seeders generated will be placed in the database/seeds directory. $ php artisan make:seeder MoviesTableSeeder Generated seeders will contain one method: run. You may insert data into your database in this method. <?php us...

Some devices connected through a serial port send data to your program at a constant rate (streaming data) or send data at unpredictable intervals. You can configure the serial port to execute a function automatically to handle data whenever it arrives. This is called the "callback function&quo...

In C, multi-line comments, /* and */, do not nest. If you annotate a block of code or function using this style of comment: /* * max(): Finds the largest integer in an array and returns it. * If the array length is less than 1, the result is undefined. * arr: The array of integers to search....

Each signed integer type may be represented in any one of three formats; it is implementation-defined which one is used. The implementation in use for any given signed integer type at least as wide as int can be determined at runtime from the two lowest-order bits of the representation of value -1 ...

Resolving scoped services during application startup can be difficult, because there is no request and hence no scoped service. Resolving a scoped service during application startup via app.ApplicationServices.GetService<AppDbContext>() can cause issues, because it will be created in the sc...

When write() is called for a named or unnamed pipe or stream socket whose reading end is closed, two things happen: POSIX.1-2001 SIGPIPE signal is sent to the process that called write() POSIX.1-2004 SIGPIPE signal is sent to the thread that called write() EPIPE error is returned ...