The PHP function file_get_contents reads the entire contents of a file into a string, while the function file reads a file into an array. file_get_contents('filename') is equivalent to implode('', file('filename')) : <?php // reads entire file into array, one elem...

You can check the version of PHP by the function phpversion function, or the PHP_VERSION constant. <?php // PHP version echo phpversion(), "\n"... The function phpinfo prints extensive info about PHP. <?php echo phpinfo(); ?>

A static variable in PHP functions and methods keeps its value after the function/method scope is exited, just like static variables in C. A static variable in a class is a class variable, and is accessed by the class name. In the global scope, static has no special meaning. test.php: <?php include("test.inc"); include("... test.inc: <?php static $i = 0; $i++; echo __FILE__,... Output: E:\phpwork\test.inc included: 1 E:\phpwork\test...

The function include includes the specified file multiple times, while include_once only includes the file once. This is a test: Create file test.php with contents: <?php for ($i = 0; $i < 5; $i++) { inclu... Create file test.inc with contents: <?php echo __FILE__, " included: $i\n"; ?> ... Run test.php , the output is: E:\phpwork\test.inc included: 0 E:\phpwork\test... Change include to include_once , only one line is printed: E:\phpwork\test.inc included: 0 You must use include_once to avoid duplicate includes in the case A includes B and C , but B and C both includes D . The relationship between require and require_once is the same.

The PHP function is_resource returns TRUE if a variable is a resource. This may come in handy when a function you are calling returns mixed type. For example mysql_query returns TRUE or FALSE for INSERT , UPDATE , DELETE etc., but returns resource or FALSE for SELECT , SHOW , or DESCRIBE . <?php $rows = array(); if ($res = mysql_quer...

The PHP function strval returns the string value of a variable. It does the same thing as casting a variable to string, or automatic conversion where string is expected. Conversion rules: Type String Value Boolean TRUE '1' Boolean FALSE '' (empty string) integer of float string representing the number Array The string 'Array' Object Result of __toString() if defined, error otherwise Resource 'Resource id #n' , where n is a number assigned to the resource. NULL '' (empty string) Example: <?php set_error_handler(function($errno, $errst... Results: bool(true) --------------------- strval: '1'...

These error level constants are defined in PHP : Constant Value Description E_ERROR 1 Fatal run-time errors. Execution of the script is halted. E_WARNING 2 (1<<1) Run-time warnings (non-fatal errors). Execution of the script is not halted. E_PARSE 4 (1<<2) Compile-time parse errors. Parse errors should only be generated by the parser. E_NOTICE 8 (1<<3) Notices. Indicate that the script encountered something that could indicate an error, but could also happen in the normal course of running a script. E_CORE_ERROR 16 (1<<4) Fatal errors that occur during PHP's initial startup. This is like an E_ERROR, except it is generated by the core of PHP. E_CORE_WARNING 32 (1<<5) Warnings (non-fatal errors) that occur during PHP's initial startup. This is like an E_WARNING, except it is generated...

A PHP try catch block looks like this: <?php try { throw new MyException('foo!'... Normally, no exceptions are thrown from internal function errors. For example: <?php $a = 1; $b = 0; try { $v = $... The division by zero error is never caught as an exception. However , you can translate errors into exceptions with an error handler and ErrorException : <?php function exception_error_handler($errno, ... which prints: Exception: exception 'ErrorException' with message... PHP does not support finally clause.

The PHP function ctype_digit returns true when all characters in a string is numeric. Use this function only on strings. You get unexpected results with other data types. Example: <?php $a = array("124.34", "00088760", "1.3e5",... Results: string(6) "124.34" ----------------- ctype_d...

The PHP function intval returns the integer value of a variable. But there are some gotchas: The string ' 0x10 ' may look like hex, but it's not recognized as hex by intval unless base 0 is entered as the second argument. With floating point numbers, round-off errors may produce surprising results (actually, intval truncates, it doesn't round off). The number base argument is effective only when the variable is a string. Examples: <?php echo 19.99 * 100, "\n"; // 1999 echo i...