• Home
• Ajax
• Prototype Ajax
• Ajax Edit In Place
• Ajax Simple Example
• Ajax Login Script
• Prototype Ajax Simple Eg.
• Submit Form - Ajax
• Multiple Image Upload
• Image Upload Ajax
• Image Upload Ajax 2
• Image Upload Using Zip File
• Crop Image
• Crop Mootool Image
• Ajax Comment
• Ajax Rating
• SuPHP
• SuPHP PDF
• Who is
• Htaccess Editor
• Light Box
• Modal Box
• Slide Show
• MYSQL FUNCTION

PHP Syntax and data types

Posted by: Asif D. Khalyani

Syntax

PHP only parses code within its delimiters. Anything outside its delimiters is sent directly to the output and is not parsed by PHP. The most common delimiters are <?php and ?>, which are open and close delimiters respectively. <script language="php"> and </script> delimiters are also available. Short tags (<? or <?= and ?>) are also commonly used, but like ASP-style tags (<% or <%= and %>), they are less portable as they can be disabled in the PHP configuration. For this reason, the use of short tags and ASP-style tags is discouraged.[31] The purpose of these delimiters is to separate PHP code from non-PHP code, including HTML. Everything outside the delimiters is ignored by the parser and is passed through as output.

Variables are prefixed with a dollar symbol and a type does not need to be specified in advance. Unlike function and class names, variable names are case sensitive. Both double-quoted ("") and heredoc strings allow the ability to embed the variable's value into the string.[33] PHP treats newlines as whitespace in the manner of a free-form language (except when inside string quotes), and statements are terminated by a semicolon. PHP has three types of comment syntax: /* */ serves as block comments, and // as well as # are used for inline comments. To output text to the browser, either the print function or the echo function is used. Both functions are nearly identical; the major difference is that print is slower than echo because the former will return a status indicating if it was successful or not, whereas the latter does not return a status and only returns the text for output.

Data types

PHP stores whole numbers in a platform-dependent range. This range is typically that of 32-bit signed integers. Unsigned integers are converted to signed values in certain situations; this behavior is different from other programming languages. Integer variables can be assigned using decimal (positive and negative), octal, and hexadecimal notations. Real numbers are also stored in a platform-specific range. They can be specified using floating point notation, or two forms of scientific notation.[38] PHP has a native Boolean type that is similar to the native Boolean types in Java and C++. Using the Boolean type conversion rules, non-zero values are interpreted as true and zero as false, as in Perl and C++. The null data type represents a variable that has no value. The only value in the null data type is NULL. Variables of the "resource" type represent references to resources from external sources. These are typically created by functions from a particular extension, and can only be processed by functions from the same extension; examples include file, image, and database resources. Arrays can contain elements of any type that PHP can handle, including resources, objects, and even other arrays. Order is preserved in lists of values and in hashes with both keys and values, and the two can be intermingled. PHP also supports strings, which can be used with single quotes, double quotes, or heredoc syntax.

Back to Index Page