![PHP Programming at Wikibooks. PHP is a general-purpose scripting language geared towards web development. [9] It was originally created by Danish-Canadian programmer Rasmus Lerdorf in 1993 and released in 1995. [10] [11] The PHP reference implementation is now produced by the PHP Group. [12] PHP was originally an abbreviation of Personal Home .... Homey hot pot and sushi buffet](/img/512x512/1298103323581.webp)
Also, you can increase PHP’s memory limit for specific websites. One method would be to place a php.ini file in the site’s webroot. You can even set the limit for specific scriptname.php. For example using ini_set(‘memory_limit’,’256MB’). How to increase PHP memory_limit. To increase the PHP memory limit setting, edit your PHP.ini file.The reason for the two different variations of "and" and "or" operators is that they operate at different precedences. (See Operator Precedence.)Description ¶. $_SERVER is an array containing information such as headers, paths, and script locations. The entries in this array are created by the web server, therefore there is no guarantee that every web server will provide any of these; servers may omit some, or provide others not listed here. However, most of these variables are ...PHP Operators. Operators are used to perform operations on variables and values. PHP divides the operators in the following groups: Arithmetic operators. Assignment operators. Comparison operators. Increment/Decrement operators. Logical operators. String operators.Tutorial PHP #01: Mengenal Bahasa Pemrograman PHP. Tutorial PHP #02: Persiapan Pemrograman PHP di Linux. Tutorial PHP #02: Persiapan Pemrograman PHP di Linux dengan XAMPP. Tutorial PHP #02: Persiapan Pemrograman PHP di Windows. Tutorial PHP #03: Memahami Struktur Dasar Sintaks PHP. Tutorial PHP #04: Mengenal Fungsi untuk Mencetak Teks.Aug 1, 2023 · PHP 8.3.0 RC 1 available for testing. Predefined Variables. Predefined Exceptions. Predefined Interfaces and Classes. Predefined Attributes. Supported Protocols and Wrappers. Variable and Type Related Extensions. "MyClass::myFunc () ""OtherClass::myFunc () ". A class constant, class property (static), and class function (static) can all share ... strpos () - Search For a Text Within a String. The PHP strpos () function searches for a specific text within a string. If a match is found, the function returns the character position of the first match. If no match is found, it will return FALSE.Aug 1, 2023 · The interactive shell stores your history which can be accessed using the up and down keys. The history is saved in the ~/.php_history file. The CLI SAPI provides the php.ini settings cli.pager and cli.prompt. The cli.pager setting allows an external program (such as less) to act as a pager for the output instead of being displayed directly on ... Aug 23, 2011 · Getting Started Introduction A simple tutorial Language Reference Basic syntax Types Variables Constants Expressions Operators Control Structures Functions PHP is a recursive acronym for "PHP: Hypertext Preprocessor". PHP is a server side scripting language that is embedded in HTML. It is used to manage dynamic content, databases, session tracking, even build entire e-commerce sites. It is integrated with a number of popular databases, including MySQL, PostgreSQL, Oracle, Sybase, Informix, and ... Aug 1, 2023 · The reason for the two different variations of "and" and "or" operators is that they operate at different precedences. (See Operator Precedence.) PHP can create, open, read, write, delete, and close files on the server. PHP can collect form data. PHP can send and receive cookies. PHP can add, delete, modify data in your database. PHP can be used to control user-access. PHP can encrypt data. With PHP you are not limited to output HTML. You can output images or PDF files.There is also something called a nowdoc which is like a single quote string in PHP, but these won't let you use variables inside them. It is the start of a string that uses the HEREDOC syntax. A third way to delimit strings is the heredoc syntax: <<<. After this operator, an identifier is provided, then a newline.Where src/ is the directory containing all your PHP code. Then, run the commands to build and run the Docker image: $ docker build -t my-php-app . $ docker run -d --name my-running-app my-php-app. We recommend that you add a php.ini configuration file; see the "Configuration" section for details. PHP User Defined Functions. Besides the built-in PHP functions, it is possible to create your own functions. A function is a block of statements that can be used repeatedly in a program. A function will not execute automatically when a page loads. A function will be executed by a call to the function.15. According to the article How to Get Current Datetime (NOW) with PHP, there are two common ways to get the current date. To get current datetime (now) with PHP, you can use the date class with any PHP version, or better the datetime class with PHP >= 5.2. Various date format expressions are available here.Jan 14, 2021 · Check PHP Version by Running PHP Code. The simplest method to determine the PHP version running on your website is executing a PHP file that contains the following code: <?php echo 'PHP version: ' . phpversion(); Create the file using a text editor like gedit or Notepad, and upload it to your website’s document root directory. The PHP concatenation operator (.) is used to combine two string values to create one string. .=. Concatenation assignment. PHP: Hypertext Preprocessor. popular general-purpose scripting language that is especially suited to web development. Fast, flexible and pragmatic, PHP powers everything from your blog to the most popular websites in the world. What's new in 8.2 Download. 8.2.9 · Changelog · Upgrading.Tutorial PHP #01: Mengenal Bahasa Pemrograman PHP. Tutorial PHP #02: Persiapan Pemrograman PHP di Linux. Tutorial PHP #02: Persiapan Pemrograman PHP di Linux dengan XAMPP. Tutorial PHP #02: Persiapan Pemrograman PHP di Windows. Tutorial PHP #03: Memahami Struktur Dasar Sintaks PHP. Tutorial PHP #04: Mengenal Fungsi untuk Mencetak Teks. Well organized and easy to understand Web building tutorials with lots of examples of how to use HTML, CSS, JavaScript, SQL, Python, PHP, Bootstrap, Java, XML and more. Aug 1, 2023 · Basic class definitions begin with the keyword class, followed by a class name, followed by a pair of curly braces which enclose the definitions of the properties and methods belonging to the class. The class name can be any valid label, provided it is not a PHP reserved word. A valid class name starts with a letter or underscore, followed by ... pub 2048R/31CBD89E 2016-12-08 Key fingerprint = 5289 95BF EDFB A719 1D46 839E F9BA 0ADA 31CB D89E uid Joe Watkins <[email protected]> pub rsa4096 2021-04-26 [SC] [expires: 2025-11-24] 39B6 4134 3D8C 104B 2B14 6DC3 F9C3 9DC0 B969 8544 uid [ultimate] Ben Ramsey <[email protected]> sub rsa4096 2021-04-26 [E] [expires: 2025-11-24] pub rsa4096 2021-04-01 [SC] F1F6 9223 8FBC 1666 E5A5 CCD4 199F 9DFE F6FF ...Returns a string formatted according to the given format string using the given integer timestamp (Unix timestamp) or the current time if no timestamp is given. In other words, timestamp is optional and defaults to the value of time().Jan 22, 2009 · 15. According to the article How to Get Current Datetime (NOW) with PHP, there are two common ways to get the current date. To get current datetime (now) with PHP, you can use the date class with any PHP version, or better the datetime class with PHP >= 5.2. Various date format expressions are available here. PHP Operators. Operators are used to perform operations on variables and values. PHP divides the operators in the following groups: Arithmetic operators. Assignment operators. Comparison operators. Increment/Decrement operators. Logical operators. String operators.Check PHP Version by Running PHP Code. The simplest method to determine the PHP version running on your website is executing a PHP file that contains the following code: <?php echo 'PHP version: ' . phpversion(); Create the file using a text editor like gedit or Notepad, and upload it to your website’s document root directory.Aug 1, 2023 · The simplest way to specify a string is to enclose it in single quotes (the character ' ). To specify a literal single quote, escape it with a backslash ( \ ). To specify a literal backslash, double it ( \\ ). All other instances of backslash will be treated as a literal backslash: this means that the other escape sequences you might be used to ... This package was approved as a trusted package on 30 Aug 2023. Description. PHP is an HTML-embedded scripting language. Much of its syntax is borrowed from C, Java and Perl with a couple of unique PHP-specific features thrown in. The goal of the language is to allow web developers to write dynamically generated pages quickly.PHP-PgSQL Similarly, to use PostgreSQL with PHP you should install the php-pgsql package: sudo apt install php-pgsql Configure PHP. If you have installed the libapache2-mod-php or php-cgi packages, you can run PHP scripts from your web browser. If you have installed the php-cli package, you can run PHP scripts at a terminal prompt.Aug 1, 2023 · The simplest way to specify a string is to enclose it in single quotes (the character ' ). To specify a literal single quote, escape it with a backslash ( \ ). To specify a literal backslash, double it ( \\ ). All other instances of backslash will be treated as a literal backslash: this means that the other escape sequences you might be used to ... Create an Array in PHP. In PHP, the array () function is used to create an array: array (); In PHP, there are three types of arrays: Indexed arrays - Arrays with a numeric index. Associative arrays - Arrays with named keys. Multidimensional arrays - Arrays containing one or more arrays. strpos () - Search For a Text Within a String. The PHP strpos () function searches for a specific text within a string. If a match is found, the function returns the character position of the first match. If no match is found, it will return FALSE. PHP Programs. PHP programs are frequently asked in the interview. These programs can be asked from basics, control statements, array, string, oops, file handling etc. Let's see the list of top PHP programs. 1) Sum of Digits. Write a PHP program to print sum of digits. Input: 23. Output: 5. Input: 624. Output: 12. 2) Even or odd number. Input ...FastCGI Process Manager (FPM) Installation. Configuration. Installation of PECL extensions. Introduction to PECL Installations. Downloading PECL extensions. Installing a PHP extension on Windows. Compiling shared PECL extensions with the pecl command. Compiling shared PECL extensions with phpize.Use W3Schools Spaces to build, test and deploy code. The code editor lets you write and practice different types of computer languages. It includes PHP, but you can use it for other languages too. New languages are added all the time: Learn More. Mar 15, 2022 · by Tali Smith. The fastest and easiest way to install PHP on Internet Information Services (IIS) is by using the Microsoft® Web Platform Installer (Web PI). Web PI completely automates setting up IIS, FastCGI, and the latest version of PHP from the php.net Web site. With Web PI, you can navigate to the "Web Platform" tab and select "PHP" under ... Aug 1, 2023 · The interactive shell stores your history which can be accessed using the up and down keys. The history is saved in the ~/.php_history file. The CLI SAPI provides the php.ini settings cli.pager and cli.prompt. The cli.pager setting allows an external program (such as less) to act as a pager for the output instead of being displayed directly on ... Jan 14, 2021 · Check PHP Version by Running PHP Code. The simplest method to determine the PHP version running on your website is executing a PHP file that contains the following code: <?php echo 'PHP version: ' . phpversion(); Create the file using a text editor like gedit or Notepad, and upload it to your website’s document root directory. The reason for the two different variations of "and" and "or" operators is that they operate at different precedences. (See Operator Precedence.)Required Knowledge. Before you begin this PHP tutorial, it is necessary that you have a basic understanding and experience of the following: HTML - PHP can be written with HTML, so it's essential. Basic programming knowledge - If you have any traditional programming experience like C, then learning PHP will be very easy for you.Aug 1, 2023 · Arrays. ¶. An array in PHP is actually an ordered map. A map is a type that associates values to keys. This type is optimized for several different uses; it can be treated as an array, list (vector), hash table (an implementation of a map), dictionary, collection, stack, queue, and probably more. As array values can be other array s, trees and ... There is also something called a nowdoc which is like a single quote string in PHP, but these won't let you use variables inside them. It is the start of a string that uses the HEREDOC syntax. A third way to delimit strings is the heredoc syntax: <<<. After this operator, an identifier is provided, then a newline.Create an Array in PHP. In PHP, the array () function is used to create an array: array (); In PHP, there are three types of arrays: Indexed arrays - Arrays with a numeric index. Associative arrays - Arrays with named keys. Multidimensional arrays - Arrays containing one or more arrays. PHP is an open-source, interpreted, and object-oriented scripting language that can be executed at the server-side. PHP is well suited for web development. Therefore, it is used to develop web applications (an application that executes on the server and generates the dynamic page.). PHP was created by Rasmus Lerdorf in 1994 but appeared in the ...Easy Method is: Just copy the file cmd.exe from c:/windows/system32/ and paste it to C:\xampp\php\ and run it, when the cmd opens type " php -v " without quotes and hit enter... you will get your php version.. thank youInstalled as CGI binary. Installed as an Apache module. Persistent Database Connections. — Using PHP from the command line. DTrace Dynamic Tracing. Function Reference. Affecting PHP's Behaviour. Audio Formats Manipulation. Command Line Specific Extensions.Aug 1, 2023 · FastCGI Process Manager (FPM) Installation. Configuration. Installation of PECL extensions. Introduction to PECL Installations. Downloading PECL extensions. Installing a PHP extension on Windows. Compiling shared PECL extensions with the pecl command. Compiling shared PECL extensions with phpize. Create an Array in PHP. In PHP, the array () function is used to create an array: array (); In PHP, there are three types of arrays: Indexed arrays - Arrays with a numeric index. Associative arrays - Arrays with named keys. Multidimensional arrays - Arrays containing one or more arrays.PHP Version: 4+ PHP Changelog: PHP 7.2: The headers parameter also accepts an array PHP 5.4: Added header injection protection for the headers parameter. PHP 4.3.0: (Windows only) All custom headers (like From, Cc, Bcc and Date) are supported, and are not case-sensitive. PHP 4.2.3: The parameter parameter is disabled in safe mode PHP 8.1.23 Released! is a number of the set ℤ = {..., -2, -1, 0, 1, 2, ...}. s can be specified in decimal (base 10), hexadecimal (base 16), octal (base 8) or binary (base 2) notation. The can be used to denote a negative. To use octal notation, precede the number with a (zero).PHP Operators. PHP Operator is a symbol i.e used to perform operations on operands. In simple words, operators are used to perform operations on variables or values.Nowadays, it's better to use queues than threads (for those who don't use Laravel there are tons of other implementations out there like this).. The basic idea is, your original PHP script puts tasks or jobs into a queue.Aug 1, 2023 · You can also call the script from the command line after chmod'ing the file (ie: chmod 755 file.php). On your first line of the file, enter "#!/usr/bin/php" (or to wherever your php executable is located). If you want to suppress the PHP headers, use the line of "#!/usr/bin/php -q" for your path. up. down. There is also something called a nowdoc which is like a single quote string in PHP, but these won't let you use variables inside them. It is the start of a string that uses the HEREDOC syntax. A third way to delimit strings is the heredoc syntax: <<<. After this operator, an identifier is provided, then a newline.PHP-GTK related documentation is hosted on the PHP-GTK website. Documentation of PEAR and the various packages can be found on a separate server. You can still read a copy of the original PHP/FI 2.0 Manual on our site, which we only host for historical purposes. The same applies to the PHP 3 Manual .Jan 14, 2021 · Check PHP Version by Running PHP Code. The simplest method to determine the PHP version running on your website is executing a PHP file that contains the following code: <?php echo 'PHP version: ' . phpversion(); Create the file using a text editor like gedit or Notepad, and upload it to your website’s document root directory. www.php.net – PHP distribution, tutorials, newsgroups, and more. www.phpfreaks.com - PHP and MySQL tutorials, scripts, forums, and more. www.phpbuilder.com – Collection of PHP resources. Hello World If your web server supports PHP, type this example into a text file called hello.php and access it in your browser by Nowadays, it's better to use queues than threads (for those who don't use Laravel there are tons of other implementations out there like this).. The basic idea is, your original PHP script puts tasks or jobs into a queue.Aug 1, 2023 · PHP 8.3.0 RC 1 available for testing. Predefined Variables. Predefined Exceptions. Predefined Interfaces and Classes. Predefined Attributes. Supported Protocols and Wrappers. Variable and Type Related Extensions. "MyClass::myFunc () ""OtherClass::myFunc () ". A class constant, class property (static), and class function (static) can all share ... Installed as CGI binary. Installed as an Apache module. Persistent Database Connections. — Using PHP from the command line. DTrace Dynamic Tracing. Function Reference. Affecting PHP's Behaviour. Audio Formats Manipulation. Command Line Specific Extensions.لغة PHP (والتي هي اختصارٌ تعاودي للعبارة PHP: Hypertext Preprocessor) هي لغةٌ مفتوحة المصدر شائعة الاستخدام لها مجال استخدامٍ عامٍ لكنها تناسب تطوير الويب ودمج لغة HTML معها. الذي يُميّز PHP عن الشيفرات التي ...PHP Version: 4+ PHP Changelog: PHP 7.2: The headers parameter also accepts an array PHP 5.4: Added header injection protection for the headers parameter. PHP 4.3.0: (Windows only) All custom headers (like From, Cc, Bcc and Date) are supported, and are not case-sensitive. PHP 4.2.3: The parameter parameter is disabled in safe modeFastCGI Process Manager (FPM) Installation. Configuration. Installation of PECL extensions. Introduction to PECL Installations. Downloading PECL extensions. Installing a PHP extension on Windows. Compiling shared PECL extensions with the pecl command. Compiling shared PECL extensions with phpize.Aug 1, 2023 · PHP 8.3.0 RC 1 available for testing. Predefined Variables. Predefined Exceptions. Predefined Interfaces and Classes. Predefined Attributes. Supported Protocols and Wrappers. Variable and Type Related Extensions. "MyClass::myFunc () ""OtherClass::myFunc () ". A class constant, class property (static), and class function (static) can all share ... php 是一种创建动态交互性站点的强有力的服务器端脚本语言。 php 是免费的，并且使用非常广泛。同时，对于像微软 asp 这样的竞争者来说，php 无疑是另一种高效率的选项。 适用于php初学者的学习线路和建议. php 开发工具推荐. php 在线工具 PHP User Defined Functions. Besides the built-in PHP functions, it is possible to create your own functions. A function is a block of statements that can be used repeatedly in a program. A function will not execute automatically when a page loads. A function will be executed by a call to the function.Tutorial PHP #01: Mengenal Bahasa Pemrograman PHP. Tutorial PHP #02: Persiapan Pemrograman PHP di Linux. Tutorial PHP #02: Persiapan Pemrograman PHP di Linux dengan XAMPP. Tutorial PHP #02: Persiapan Pemrograman PHP di Windows. Tutorial PHP #03: Memahami Struktur Dasar Sintaks PHP. Tutorial PHP #04: Mengenal Fungsi untuk Mencetak Teks. Use W3Schools Spaces to build, test and deploy code. The code editor lets you write and practice different types of computer languages. It includes PHP, but you can use it for other languages too. New languages are added all the time: Learn More. W3Schools offers free online tutorials, references and exercises in all the major languages of the web. Covering popular subjects like HTML, CSS, JavaScript, Python, SQL, Java, and many, many more. Description ¶. $_SERVER is an array containing information such as headers, paths, and script locations. The entries in this array are created by the web server, therefore there is no guarantee that every web server will provide any of these; servers may omit some, or provide others not listed here. However, most of these variables are ...PHP can create, open, read, write, delete, and close files on the server. PHP can collect form data. PHP can send and receive cookies. PHP can add, delete, modify data in your database. PHP can be used to control user-access. PHP can encrypt data. With PHP you are not limited to output HTML. You can output images or PDF files.The interactive shell stores your history which can be accessed using the up and down keys. The history is saved in the ~/.php_history file. The CLI SAPI provides the php.ini settings cli.pager and cli.prompt. The cli.pager setting allows an external program (such as less) to act as a pager for the output instead of being displayed directly on ...The simplest way to specify a string is to enclose it in single quotes (the character ' ). To specify a literal single quote, escape it with a backslash ( \ ). To specify a literal backslash, double it ( \\ ). All other instances of backslash will be treated as a literal backslash: this means that the other escape sequences you might be used to ...Apr 24, 2023 · PHP is a server-side scripting language, which means that a server executes the instructions in a script. Then, the server provides data on request, channels the requests, and organizes the information in a database. When a web server receives a script, it will process the request and send output to a web browser in an HTML format. Aug 1, 2023 · The simplest way to specify a string is to enclose it in single quotes (the character ' ). To specify a literal single quote, escape it with a backslash ( \ ). To specify a literal backslash, double it ( \\ ). All other instances of backslash will be treated as a literal backslash: this means that the other escape sequences you might be used to ... PHP Programs. PHP programs are frequently asked in the interview. These programs can be asked from basics, control statements, array, string, oops, file handling etc. Let's see the list of top PHP programs. 1) Sum of Digits. Write a PHP program to print sum of digits. Input: 23. Output: 5. Input: 624. Output: 12. 2) Even or odd number. Input ...Aug 1, 2023 · Command line options; Option Long Option Description-a--interactive: Run PHP interactively. For more information, see the Interactive shell section.-b--bindpath: Bind Path for external FASTCGI Server mode (CGI only). May 5, 2012 · In order to set project specific configuration options, simply add a php.ini file to your project, and then run the built-in server with this flag: php -S localhost:8000 -c php.ini. This is especially helpful for settings that cannot be set at runtime (ini_set ()). up. down.
A session is started with the session_start () function. Session variables are set with the PHP global variable: $_SESSION. Now, let's create a new page called "demo_session1.php". In this page, we start a new PHP session and set some session variables:. Tolq
Basic PHP Syntax. A PHP script can be placed anywhere in the document. The default file extension for PHP files is " .php ". A PHP file normally contains HTML tags, and some PHP scripting code. Below, we have an example of a simple PHP file, with a PHP script that uses a built-in PHP function " echo " to output the text "Hello World!" Great if you like your tutorials to the point. 11. Learn-php.org Free Interactive PHP Tutorial. Learn-php.org free interactive PHP tutorial. The unique thing about this PHP tutorial is that it’s a set of interactive exercises that encourage you to try out coding and see if you can get the expected output.Arrays. ¶. An array in PHP is actually an ordered map. A map is a type that associates values to keys. This type is optimized for several different uses; it can be treated as an array, list (vector), hash table (an implementation of a map), dictionary, collection, stack, queue, and probably more. As array values can be other array s, trees and ...There is also something called a nowdoc which is like a single quote string in PHP, but these won't let you use variables inside them. It is the start of a string that uses the HEREDOC syntax. A third way to delimit strings is the heredoc syntax: <<<. After this operator, an identifier is provided, then a newline.Select Data From a MySQL Database. The SELECT statement is used to select data from one or more tables: SELECT column_name (s) FROM table_name. or we can use the * character to select ALL columns from a table: SELECT * FROM table_name. To learn more about SQL, please visit our SQL tutorial. strpos () - Search For a Text Within a String. The PHP strpos () function searches for a specific text within a string. If a match is found, the function returns the character position of the first match. If no match is found, it will return FALSE. 7 Min Read. PHP (Hypertext Preprocessor) is known as a general-purpose scripting language that can be utilized to create intuitive and dynamic websites. It was among the pioneer server-side language that can be integrated into HTML, making it easier to include functionality to web pages without requiring to call external data.PHP Variables. A variable can have a short name (like x and y) or a more descriptive name (age, carname, total_volume). A variable starts with the $ sign, followed by the name of the variable. A variable name must start with a letter or the underscore character. A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9 ... Get the latest 1 US Dollar to Philippine Peso rate for FREE with the original Universal Currency Converter. Set rate alerts for USD to PHP and learn more about US Dollars and Philippine Pesos from XE - the Currency Authority. Aug 1, 2023 · Basic class definitions begin with the keyword class, followed by a class name, followed by a pair of curly braces which enclose the definitions of the properties and methods belonging to the class. The class name can be any valid label, provided it is not a PHP reserved word. A valid class name starts with a letter or underscore, followed by ... The PHP concatenation operator (.) is used to combine two string values to create one string. .=. Concatenation assignment.PHP: Hypertext Preprocessor. popular general-purpose scripting language that is especially suited to web development. Fast, flexible and pragmatic, PHP powers everything from your blog to the most popular websites in the world. What's new in 8.2 Download. 8.2.9 · Changelog · Upgrading.The optional timestamp parameter in the date () function specifies a timestamp. If omitted, the current date and time will be used (as in the examples above). The PHP mktime () function returns the Unix timestamp for a date. The Unix timestamp contains the number of seconds between the Unix Epoch (January 1 1970 00:00:00 GMT) and the time ...PHP supports C-style pre- and post-increment and decrement operators. Note: The increment/decrement operators only affect numbers and strings. Arrays, objects, booleans and resources are not affected. Decrementing null values has no effect too, but incrementing them results in 1. Increment/decrement Operators.PHP Create/Retrieve a Cookie. The following example creates a cookie named "user" with the value "John Doe". The cookie will expire after 30 days (86400 * 30). The "/" means that the cookie is available in entire website (otherwise, select the directory you prefer). We then retrieve the value of the cookie "user" (using the global variable ...May 5, 2012 · In order to set project specific configuration options, simply add a php.ini file to your project, and then run the built-in server with this flag: php -S localhost:8000 -c php.ini. This is especially helpful for settings that cannot be set at runtime (ini_set ()). up. down. The user friendly PHP online compiler that allows you to Write PHP code and run it online. The PHP text editor also supports taking input from the user and standard libraries..