29 September 2013

What are the Syntax of PHP programming language

  • When PHP parses a file, it looks for opening PHP tag "<?php or <?" and ending php tag " ?>" which tell PHP to start and stop interpreting the code between them. 
  • Everything outside of a pair of opening and closing tags is ignored by the PHP parser. Example:
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 <p>This is going to be ignored by PHP Parser.</p>

        <?php echo 'While this is going to be parsed.'; ?>

    <p>This will also be ignored by PHP parser.</p>
  • PHP code must have a semicolon ";" at the end of each statement.
  • The closing PHP tag "?>" automatically insert a semicolon.
  • Example:
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    <?php
        echo 'PHP is Fun to learn !!';
    ?>
    <br>
    <?php  echo 'PHP automatically insert a semicolon at the last closing tag' ?>
    <br>
    <?php echo 'If a PHP file have only PHP code than the last closing tag can be omitted';
    
  • Example Advanced escaping
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<?php

        if ($expression) {

        ?>

        <strong>This is true.</strong>

        <?php

        } else {

        ?>

        <strong>This is false.</strong>

        <?php

        }

        ?> 
  • Before PHP version 7 There were four different pairs of opening and closing tags which could be used in PHP. Standard tag is always available Example: Script tag is also always available Example:
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<script language="php">echo 'some editors (like FrontPage) don\'t like processing instructions';

            </script>
  • Short tags can be turned on and off from the php.ini configuration file. Example:
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<?= expression ?>
  • This is a shortcut for
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<? echo expression ?>
  • ASP style tags can be turned on and off from the php.ini configuration file Example:
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<% echo 'You may optionally use ASP-style tags'; %><%= $variable; # This is a shortcut for "<% echo . . ." %>

PHP for the Web: Visual QuickStart Guide (5th Edition)

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