Category: php

PHP – Deprecated Features ”; Previous Next As some new features are added with each new version, some features are also removed as they are deemed to be obsolete. In this chapter, we have a look at deprecated features after PHP version 5. Deprecated in PHP Ver 7 PHP 4 Style Constructors PHP 4 style Constructors are methods having same name as the class they are defined in, are now deprecated, and will be removed in the future. PHP 7 will emit E_DEPRECATED if a PHP 4 constructor is the only constructor defined within a class. Classes implementing a __construct() method are unaffected. Example Take a look at the following example − <?php class A { function A() { print(”Style Constructor”); } } ?> It produces the following output on the browser − Deprecated: Methods with the same name as their class will not be constructors in a future version of PHP; A has a deprecated constructor in… Static Calls to Non-static Methods Static calls to non-static methods are deprecated, and may be removed in the future. Example Take a look at the following example − <?php class A { function b() { print(”Non-static call”); } } A::b(); ?> It produces the following output on the browser − Deprecated: Non-static method A::b() should not be called statically in… Non-static call password_hash() salt option The salt option for the password_hash() function has been deprecated so that the developers do not generate their own (usually insecure) salts. The function itself generates a cryptographically secure salt, when no salt is provided by the developer – thus custom salt generation is not required any more. capture_session_meta SSL context option The capture_session_meta SSL context option has been deprecated. SSL metadata is now used through the stream_get_meta_data() function. ext/mcrypt The mcrypt extension has been deprecated in favour of OpenSSL. Unquoted Strings Unquoted strings that are non-existent global constants are taken to be strings of themselves. This behaviour used to emit an E_NOTICE, but will now emit an E_WARNING. In the next major version of PHP, an Error exception will be thrown instead. The __autoload() Method The __autoload() method has been deprecated because it is inferior to spl_autoload_register() (due to it not being able to chain autoloaders), and there is no interoperability between the two autoloading styles. The create_function() Function Given the security issues of this function has now been deprecated. The preferred alternative is to use anonymous functions. The each() Function This function causes implementation issues for some language changes. It has therefore been deprecated. Case-Insensitive Constants The declaration of case-insensitive constants has been deprecated. Passing true as the third argument to define() will now generate a deprecation warning. The (real) and is-real() Function The (real) cast is deprecated, use (float) instead. The is_real() function is also deprecated, use is_float() instead. The “parent” Leyword Using parent inside a class without a parent is deprecated, and will throw a compile-time error in the future. Currently an error will only be generated if/when the parent is accessed at run-time. Deprecated in PHP Ver 8 If a parameter with a default value is followed by a required parameter, the default value has no effect. This is deprecated as of PHP 8.0.0 and can generally be resolved by dropping the default value, without a change in functionality − <?php function test($a = [], $b) {} // Before function test($a, $b) {} // After ?> One exception to this rule are parameters of the form Type $param = null, where the null default makes the type implicitly nullable. This usage remains allowed, but it is recommended to use an explicit nullable type instead − <?php function test(A $a = null, $b) {} // Still allowed function test(?A $a, $b) {} // Recommended ?> Calling get_defined_functions() with exclude_disabled explicitly set to false is deprecated and no longer has an effect. get_defined_functions() will never include disabled functions. Sort comparison functions that return true or false will now throw a deprecation warning, and should be replaced with an implementation that returns an integer less than, equal to, or greater than zero. <?php // Replace usort($array, fn($a, $b) => $a > $b); // With usort($array, fn($a, $b) => $a <=> $b); ?> Implicit Incompatible float to int Conversions The implicit conversion of float to int which leads to a loss in precision is now deprecated. This affects array keys, int type declarations in coercive mode, and operators working on ints. Calling a Static Element on a Trait Calling a static method, or accessing a static property directly on a trait is deprecated. Static methods and properties should only be accessed on a class using the trait. Date Functions date_sunrise() and date_sunset() have been deprecated. Use date_sun_info() instead. strptime() has been deprecated. Use date_parse_from_format() instead (for locale-independent parsing), or IntlDateFormatter::parse() (for locale-dependent parsing). strftime() and gmstrftime() have been deprecated. You can use date() instead (for locale-independent formatting), or IntlDateFormatter::format() (for locale-dependent formatting). Dynamic Properties The creation of dynamic properties is deprecated. Instead, use stdClass that allows dynamic properties. Print Page Previous Next Advertisements ”;

PHP – String Operators ”; Previous Next There are two operators in PHP for working with string data types: concatenation operator (“.”) and the concatenation assignment operator (“.=”). Read this chapter to learn how these operators work in PHP. Concatenation Operator in PHP The dot operator (“.”) is PHP”s concatenation operator. It joins two string operands (characters of right hand string appended to left hand string) and returns a new string. $third = $first . $second; Example The following example shows how you can use the concatenation operator in PHP − <?php $x=”Hello”; $y=” “; $z=”PHP”; $str=$x . $y . $z; echo $str; ?> It will produce the following output − Hello PHP Concatenation Assignment Operator in PHP PHP also has the “.=” operator which can be termed as the concatenation assignment operator. It updates the string on its left by appending the characters of right hand operand. $leftstring .= $rightstring; Example The following example uses the concatenation assignment operator. Two string operands are concatenated returning the updated contents of string on the left side − <?php $x=”Hello “; $y=”PHP”; $x .= $y; echo $x; ?> It will produce the following output − Hello PHP Print Page Previous Next Advertisements ”;

Discuss PHP ”; Previous Next The PHP Hypertext Preprocessor (PHP) is a programming language that allows web developers to create dynamic content that interacts with databases. PHP is basically used for developing web based software applications. This tutorial helps you to build your base with PHP. Print Page Previous Next Advertisements ”;

PHP – Type Juggling ”; Previous Next PHP is known as a dynamically typed language. The type of a variable in PHP changes dynamically. This feature is called “type juggling” in PHP. In C, C++ and Java, you need to declare the variable and its type before using it in the subsequent code. The variable can take a value that matches with the declared type only. Explicit type declaration of a variable is neither needed nor supported in PHP. Hence the type of PHP variable is decided by the value assigned to it, and not the other way around. Further, when a variable is assigned a value of different type, its type too changes. Example 1 Look at the following variable assignment in PHP. <?php $var = “Hello”; echo “The variable $var is of ” . gettype($var) . ” type” .PHP_EOL; $var = 10; echo “The variable $var is of ” . gettype($var) . ” type” .PHP_EOL; $var = true; echo “The variable $var is of ” . gettype($var) . ” type” .PHP_EOL; $var = [1,2,3,4]; echo “The variable $var is of ” . gettype($var) . ” type” .PHP_EOL; ?> It will produce the following output − The variable $var is of string type The variable $var is of integer type The variable $var is of boolean type The variable $var is of array type You can see the type of “$var” changes dynamically as per the value assigned to it. This feature of PHP is called “type juggling”. Example 2 Type juggling also takes place during calculation of expression. In this example, a string variable containing digits is automatically converted to integer for evaluation of addition expression. <?php $var1=100; $var2=”100″; $var3=$var1+$var2; var_dump($var3); ?> Here is its output − int(200) Example 3 If a string starts with digits, trailing non-numeric characters if any, are ignored while performing the calculation. However, PHP parser issues a notice as shown below − <?php $var1=100; $var2=”100 days”; $var3=$var1+$var2; var_dump($var3); ?> You will get the following output − int(200) PHP Warning: A non-numeric value encountered in /home/cg/root/53040/main.php on line 4 Type Casting vs Type Juggling Note that “type casting” in PHP is a little different from “type juggling”. In type juggling, PHP automatically converts types from one to another when necessary. For example, if an integer value is assigned to a variable, it becomes an integer. On the other hand, type casting takes place when the user explicitly defines the data type in which they want to cast. Example Type casting forces a variable to be used as a certain type. The following script shows an example of different type cast operators − <?php $var1=100; $var2=(boolean)$var1; $var3=(string)$var1; $var4=(array)$var1; $var5=(object)$var1; var_dump($var2, $var3, $var4, $var5); ?> It will produce the following output − bool(true) string(3) “100” array(1) { [0]=> int(100) } object(stdClass)#1 (1) { [“scalar”]=> int(100) } Example Casting a variable to a string can also be done by enclosing in double quoted string − <?php $var1=100.50; $var2=(string)$var1; $var3=”$var1″; var_dump($var2, $var3); ?> Here, you will get the following output − string(5) “100.5” string(5) “100.5” Print Page Previous Next Advertisements ”;

PHP – Closure::call() ”; Previous Next In PHP, a closure is an anonymous function that has access to the variables in the scope in which it was created, even after that scope has closed. You need to specify use keyword in it. Closures are objects that encapsulate the function code and the scope in which they were created. With PHP 7, a new closure::call() method was introduced to bind an object scope to a closure and invoke it. Methods in the Closure Class The Closure class has the following methods including the call() method − final class Closure { /* Methods */ private __construct() public static bind(Closure $closure, ?object $newThis, object|string|null $newScope = “static”): ?Closure public bindTo(?object $newThis, object|string|null $newScope = “static”): ?Closure public call(object $newThis, mixed …$args): mixed public static fromCallable(callable $callback): Closure } The call() method is a static method of Closure class. It has been introduced as a shortcut the bind() or bindTo() methods. The bind() method Duplicates a closure with a specific bound object and class scope while the bindTo() method duplicates the closure with a new bound object and class scope. The call() method has the following signature − public Closure::call(object $newThis, mixed …$args): mixed The call() method temporarily binds the closure to newThis, and calls it with any given parameters. With version prior to PHP 7, the bindTo() method can be used as follows − <?php class A { private $x = 1; } // Define a closure Pre PHP 7 code $getValue = function() { return $this->x; }; // Bind a clousure $value = $getValue->bindTo(new A, ”A”); print($value()); ?> The program binds the $getValue which is a closure object, to the object of A class and prints the value of its private variable $x – it is 1. With PHP 7, the binding is achieved by call() method as shown below − <?php class A { private $x = 1; } // PHP 7+ code, Define $value = function() { return $this->x; }; print($value->call(new A)); ?> Print Page Previous Next Advertisements ”;

PHP – PEAR ”; Previous Next PEAR is an acronym for PHP Extension and Application Repository. It is a repository of PHP packages or extensions. You can freely incorporate any of these extensions from PEAR in your code. The PEAR project was established by Stig S. Bakken in 1999. Most of the precompiled distributions of PHP such as XAMPP already have PEAR bundled with it. If not, you can install PEAR by downloading go-pear.phar file from https://pear.php.net/go-pear.phar and run php go-pear.phar In a Windows Command Prompt to start the installation. Based on your responses to the setup steps, the PEAR Package Manager will be installed in the path, specified during installation. You can then add that installation path to your PATH environment. Either do this manually (Start > Control Panel > System > Environment) or run (double-click) the newly generated PEAR_ENV.reg that”s now found in the PHP source directory. You can now access the PEAR Package Manager by running the command − C:xamppphp>pear In a Windows Command Prompt. You will get the list of PEAR commands as follows − C:xamppphp>pear Commands: build Build an Extension From C Source bundle Unpacks a Pecl Package channel-add Add a Channel channel-alias Specify an alias to a channel name channel-delete Remove a Channel From the List channel-discover Initialize a Channel from its server channel-info Retrieve Information on a Channel channel-login Connects and authenticates to remote channel server channel-logout Logs out from the remote channel server channel-update Update an Existing Channel clear-cache Clear Web Services Cache config-create Create a Default configuration file config-get Show One Setting config-help Show Information About Setting config-set Change Setting config-show Show All Settings convert Convert a package.xml 1.0 to package.xml 2.0 format cvsdiff Run a “cvs diff” for all files in a package cvstag Set CVS Release Tag download Download Package download-all Downloads each available package from the default channel info Display information about a package install Install Package list List Installed Packages In The Default Channel list-all List All Packages list-channels List Available Channels list-files List Files In Installed Package list-upgrades List Available Upgrades login Connects and authenticates to remote server [Deprecated in favor of channel-login] logout Logs out from the remote server [Deprecated in favor of channel-logout] makerpm Builds an RPM spec file from a PEAR package package Build Package package-dependencies Show package dependencies package-validate Validate Package Consistency pickle Build PECL Package remote-info Information About Remote Packages remote-list List Remote Packages run-scripts Run Post-Install Scripts bundled with a package run-tests Run Regression Tests search Search remote package database shell-test Shell Script Test sign Sign a package distribution file svntag Set SVN Release Tag uninstall Un-install Package update-channels Update the Channel List upgrade Upgrade Package upgrade-all Upgrade All Packages [Deprecated in favor of calling upgrade with no parameters] Installing packages with PEAR is so easy. One way to find packages, is using the official PEAR site https://pear.php.net/packages.php and then run pear install <package-name> The next step is to use the PEAR package in your code. To do that, you should include the main PHP script of the package in your program with include, require, include_once or require_once statements. <?php include “PEARPACKAGE.php”; . . . . . // rest of the code . . . . . ?> A newer PHP package manager called Composer is an alternative available for managing packages for a PHP project. Composer also supports the installation of PEAR packages. Composer is preferred by many instead of PEAR for PHP package distribution. Print Page Previous Next Advertisements ”;

PHP – Syntax ”; Previous Next The syntax rules of PHP are very similar to C Language. PHP is a server side scripting language. A PHP code is stored as a text file with “.php” extension. A “.php” file is essentially a web page with one or more blocks of PHP code interspersed in the HTML script. However, it must be opened in a browser with a HTTP protocol URL. In other words, if you double-click on the PHP file icon, it will be opened locally with the file protocol. For example, if you open the “index.php” file in the document root folder of your Apache server, it may just show the text of the PHP code. However, if you launch the Apache server and open the URL http://localhost/index.php, it displays the Apache home page. A “.php” file may contain HTML, CSS and JavaScript code blocks along with the PHP code. Hence, the PHP parser must differentiate between the PHP code from the other elements. When a “.php” file is opened in the web browser, the HTML engine renders the HTML/CSS/JavaScript part and escapes out of the HTML block as soon as the statements included in PHP tags are encountered. The PHP parser interpreter processes this block and returns the response to the browser. PHP defines two methods of using tags for escaping the PHP code from HTML. Canonical PHP tags and Short-open (SGML-style) tags. Canonical PHP Tags The most universally effective PHP tag style is − <?php One or more PHP statements ?> If you use this style, you can be positive that your tags will always be correctly interpreted. Short-open (SGML-style) Tags Short or short-open tags look like this − <?php One or more PHP statements ?> Short tags are, as one might expect, the shortest option. You must do one of two things to enable PHP to recognize the tags − Choose the “–enable-short-tags” configuration option when you”re building PHP. Set the “short_open_tag” setting in your php.ini file to on. short_open_tag=on This option must be disabled to parse XML with PHP because the same syntax is used for XML tags. The use of ASP-style tags − <%…%> and HTML script tags − <script language = “PHP”>…</script> has been discontinued. Escaping from HTML The PHP parser ignores everything outside of a pair of opening and closing tags. Thus, a PHP file can have mixed content. This allows PHP to be embedded in HTML documents − <p>This is a HTML statement</p> <?php echo This is a PHP statement.”; ?> <p>This is another HTML statement.</p> A little advanced example of escaping using conditions is shown below − <?php if ($expression == true): ?> This HTML statement will be rendered. <?php else: ?> Otherwise this HTML statement will be rendered. <?php endif; ?> PHP skips the blocks where the condition is not met, even though they are outside of the PHP open/close tags. For outputting large blocks of text, dropping out of PHP parsing mode is generally more efficient than sending all of the text through echo or print. Basic Syntax of PHP The basic syntax of PHP is very similar to that of C and C++. Statements are expressions terminated by semicolons A statement in PHP is any expression that is followed by a semicolon (;). Any sequence of valid PHP statements that is enclosed by the PHP tags is a valid PHP program. Here is a typical statement in PHP, which in this case assigns a string of characters to a variable called “$greeting” − $greeting = “Welcome to PHP!”; A physical line in the text editor doesn’t have any significance in a PHP code. There may be multiple semicolon-terminated statements in a single line. On the other hand, a PHP statement may spill over more than one line if required. Expressions are combinations of tokens The smallest building blocks of PHP are the indivisible tokens such as numbers (3.14159), strings (“two”), variables ($two), constants (TRUE), and the special words that make up the syntax of PHP itself like “if”, “else”, “while”, “for”, and so forth. Braces make blocks Although statements cannot be combined like expressions, you can always put a sequence of statements anywhere a statement can go, by enclosing them in a set of curly braces. Here, both the following statements are equivalent − if (3 == 2 + 1) print(“Good – I haven”t totally lost my mind.”); if (3 == 2 + 1) { print(“Good – I haven”t totally”); print(“lost my mind.”); } PHP is case sensitive PHP is a case sensitive language. The names of various PHP identifiers such as variable, function, class, etc., are case sensitive. As a result, the variable “$age” is not the same as “$Age”. Similarly, a function called “myfunction()” is different from another function called “MyFunction()”. Print Page Previous Next Advertisements ”;

PHP – Exceptions ”; Previous Next Prior to version 7, PHP parser used to report errors in response to various conditions. Each error used to be of a certain predefined type. PHP7 has changed the mechanism of error reporting. Instead of traditional error reporting, most errors are now reported by throwing error exceptions. The exception handling mechanism in PHP is similar to many other languages, and is implemented with the try, catch, throw and finally keywords. The Throwable Interface Exceptions in PHP implements the Throwable interface. The Throwable interface acts as the base for any object that can be thrown via throw statement, including Error and Exception objects. A user defined class cannot implement Throwable interface directly. Instead, to declare a user defined exception class, it must extend the Exception class. PHP code with potential exceptions is surrounded in a try block. An exception object is thrown if it is found, to facilitate the catching of potential exceptions. Each try must have at least one corresponding catch or finally block. Moreover, there may be more than one catch/finally blocks corresponding to a try block. try { // throw errors in the try-block // if an error occurs we can throw an exception throw new Exception(”this is an error.”); } catch(Exception $e) { // catch the throws in the catch-block // do something with the exception object, eg. // display its message echo ”Error message: ” .$e->getMessage(); } If an exception is thrown and there is no catch block, the exception will “bubble up” until it finds a matching catch block. If the call stack is unwound all the way to the global scope without encountering a matching catch block, a global exception handler will be called (if it is set) otherwise the program will terminate with a fatal error. set_exception_handler This function sets the default exception handler if an exception is not caught within a try/catch block. After the callback is executed, the program execution will stop. set_exception_handler(?callable $callback): ?callable The $callback parameter is the name of the function to be called when an uncaught exception occurs. This function must be defined before calling set_exception_handler(). This handler function needs to accept one parameter, which will be the exception object that was thrown. The function returns the name of the previously defined exception handler, or NULL on error. If no previous handler was defined, NULL is also returned. Example Take a look at the following example − <?php function handler($ex) { echo “Uncaught exception is : ” , $ex->getMessage(), “n”; } set_exception_handler(”handler”); throw new Exception(”Not Found Exception”); echo “not included Executedn”; ?> It will produce the following output − Uncaught exception is : Not Found Exception SPL Exceptions Standard PHP library contains predefined exceptions − Sr.No Predefined Exceptions 1 LogicException Exception that represents error in the program logic. 2 BadFunctionCallException Exception thrown if a callback refers to an undefined function or if some arguments are missing. 3 BadMethodCallException Exception thrown if a callback refers to an undefined method or if some arguments are missing. 4 DomainException Exception thrown if a value does not adhere to a defined valid data domain. 5 InvalidArgumentException Exception thrown if an argument is not of the expected type. 6 LengthException Exception thrown if a length is invalid. 7 OutOfRangeException Exception thrown when an illegal index was requested. 8 RuntimeException Exception thrown if an error which can only be found on runtime occurs. 9 OutOfBoundsException Exception thrown if a value is not a valid key. 10 OverflowException Exception thrown when adding an element to a full container. 11 RangeException Exception thrown to indicate range errors during program execution. An arithmetic error other than under/overflow. 12 UnderflowException Exception thrown when performing an invalid operation on an empty container, such as removing an element. 13 UnexpectedValueException Exception thrown if a value does not match with a set of values. User-defined Exception You can define a custom exception class that extends the base Exception class. Following script defines a custom exception class called myException. This type of exception is thrown if value of $num is less than 0 or greater than 100. Example The getMessage() method of Exception class returns the error message and getLine() method returns line of code in which exception appears. <?php class myException extends Exception { function message() { return “error : “. $this->getMessage(). “in line no”. $this->getLine(); } } $num=125; try { if ($num>100 || $num<0) throw new myException(“$num is invalid number”); else echo “$num is a valid number”; } catch (myException $m) { echo $m->message(); } ?> Run the above code with $num=125 and $num=90 to get an error message and a message of valid number − error : 125 is invalid number in line no 10 Print Page Previous Next Advertisements ”;

PHP – Features ”; Previous Next PHP (Hypertext Preprocessor) is an open-source server-side scripting language primarily used for web development. PHP can be embedded into HTML code. PHP is mainly used for server-side scripting, which runs scripts on the web server and then forwards the HTML they process to the web browser on the client. This makes it possible for programmers to design dynamic webpages that can manage sessions, handle forms, communicate with databases, and carry out a variety of other duties necessary for online applications. Features of PHP Over the years, PHP has incorporated numerous features. It is being consistently upgraded with new features and code revisions. In this chapter, let”s highlight some of the key features of PHP: PHP is Simple and Easy to Learn The syntax of PHP compared to that of C, Java, and Perl, which makes it rather simple for developers to comprehend, particularly for those who are already familiar with other programming languages. Web apps can be developed quickly because of its generous pre-defined functions. PHP is Open Source PHP is free and open-source, meaning we can download it for free, and anyone can use it, modify it, and distribute. This encourages a sizable and vibrant developer community that uses forums, tutorials, and documentation to support and contribute to its development. PHP is Cross-Platform Compatible Numerous operating systems including Windows, Linux, macOS, and UNIX; and different databases like MongoDB, PostgreSQL, MySQL are compatible with PHP. PHP-based apps can operate on several environments without requiring any modifications due to this cross-platform inter-operability. Server-Side Scripting in PHP PHP is mainly used for server-side scripting, which runs scripts on the web server and then forwards the HTML they process to the web browser on the client. It helps the developers in Form Submission and Session Management with users across multiple requests. PHP Supports Easy Integration with Databases PHP offers strong database interaction support for various DBMS. It offers numerous built-in functions to achieve the database connection. PHP also includes database abstraction layer which integrates the communication between the application and the database. This makes it simple for developers to design database-driven web applications. PHP Provides Extensive Library Support PHP provides extensive libraries for various functionalities like image processing, encryption, PDF generation, parsing XML and JSON, handling sessions and cookies, and much more. Security Features in PHP PHP provides a plethora of built-in functions for data encryption. Developers can also leverage third-party applications for security. PHP employs security algorithms like Sha1 and MD5 to encrypt strings. Additionally, functions like filter_var and strip_tags contribute in maintaining a secure environment for the users. PHP also supports secure communication protocols like HTTPS. Efficient Memory and Session Management in PHP PHP is a reliable language due to its efficient memory management and session management. It avoids unnecessary memory allocation. PHP code runs in its own memory space which makes it faster compared to other scripting languages making it more efficient. In PHP, the database connections are also fast. PHP Has Active Community and Support Since PHP is an open-source platform, it has a vibrant community of developers who actively contribute to its development, share knowledge, provide support, and create third-party tools and frameworks. Due to this active community support, PHP remains up-to-date and developers can easily seek help from other community members in case they get any errors or exceptions while writing PHP codes. Print Page Previous Next Advertisements ”;

PHP For C Developers ”; Previous Next If you have a prior knowledge of C programming, learning PHP becomes a lot easier, especially the basics. Although PHP is a lot like C, it is bundled with a whole lot of Web-specific libraries, with everything hooked up directly to your favorite Web server. The simplest way to think of PHP is as interpreted C that you can embed in HTML documents. PHP script can also be executed from the command line, much like a C program. The syntax of statements and function definitions should be familiar, except that variables are always preceded by $, and functions do not require separate prototypes. Let us take a look at some of the similarities and differences in PHP and C − Similarities Between C and PHP Syntax − Broadly speaking, PHP syntax is the same as in C, which is what makes learning PHP easier, if you are already conversant with C. Similar to C, PHP Code is blank insensitive, statements are terminated with semicolons. function calls have the same structure my_function(expression1, expression2) { Statements; } Curly brackets are used to put multiple statements into blocks. PHP supports C and C++-style comments (/* */ as well as //), and also Perl and shell-script style (#). Operators − The assignment operators (=, +=, *=, and so on), the Boolean operators (&&, ||, !), the comparison operators (<,>, <=, >=, ==, !=), and the basic arithmetic operators (+, -, *, /, %) all behave in PHP as they do in C. Control Structures − The basic control structures (if, switch, while, for) behave as they do in C, including supporting break and continue. One notable difference is that switch in PHP can accept strings as case identifiers. PHP also has foreach looping construct that traverses the collections such as arrays. Function Names − As you peruse the documentation, you.ll see many function names that seem identical to C functions. Differences Between C and PHP Dollar Sign − All variable names are prefixed with a leading $. Variables do not need to be declared in advance of assignment, and they have no intrinsic type. PHP is a dynamically typed language, as against C being a statically typed language. Types − PHP has only two numerical types: integer (corresponding to a long in C) and double (corresponding to a double in C). In PHP, float is synonymous to double. Strings are of arbitrary length. There is no separate char type in PHP, as is the case in C. Type Conversion − C is a strongly typed language, as type of a variable must be declared before using, and the types are checked at compile time. PHP on the other hand, is a weakly typed language, types are not checked at compile time, and type errors do not typically occur at runtime either. Instead, variables and values are automatically converted across types as needed. Arrays − Arrays have a syntax superficially similar to C”s array syntax, but they are implemented completely differently. In C, an array is a collection of similar data types. In a PHP array, the items may be of different types. PHP arrays are actually associative arrays or hashes, and the index can be either a number or a string. They do not need to be declared or allocated in advance. No Struct Type − The struct keyword in C is used to define a new data type. There is no struct keyword or its equivalent in PHP, partly because the array and object types together make it unnecessary. The elements of a PHP array need not be of a consistent type. No Pointers − Pointers are an important concept in C. There are no pointers available in PHP, although the tapeless variables play a similar role. Unlike C, PHP does support variable references. You can also emulate function pointers to some extent, in that function names can be stored in variables and called by using the variable rather than a literal name. No Prototypes − Functions do not need to be declared before their implementation is defined, as long as the definition can be found somewhere in the current code file or included files. On the contrary, a C function must defined before it is used. No main() − In a C program, the main() function is the entry point, irrespective of where it is present in the code. A PHP program on the other hand starts execution from the first statement in the script Memory Management − The PHP engine is effectively a garbage-collected environment (reference-counted), and in small scripts there is no need to do any deallocation. You should freely allocate new structures – such as new strings and object instances. IN PHP5, it is possible to define destructor for objects, but there is are no free or delete keywords as in C/C++. Destructor are called when the last reference to an object goes away, before the memory is reclaimed. Compilation and Linking − PHP is an interpreted language. Hence, the compiled version of PHP script is not created. A C program is first compiled to obtain the object code, which is then linked to the required libraries to build an executable. There is no separate compilation step for PHP scripts. A PHP script cannot be turned into a self executable. Permissiveness − As a general matter, PHP is more forgiving than C (especially in its type system) and so will let you get away with new kinds of mistakes. Unexpected results are more common than errors. Print Page Previous Next Advertisements ”;