Binita's REGEXform

REGEX:

Pattern:  
String:  

Regular Expression	Will match...
/foo/	The string "foo"
/^foo/	'foo' at the start of a string
/foo$/	'foo' at the end of a string
/^foo$/	'foo' when it is alone on a string
/[abc]/	a, b, or c
/[a-z]/	Any lowercase letter
/[^A-Z]/	Any character that is not a uppercase letter
/(gif|jpeg)/	Matches either 'gif' or 'jpeg'
/[a-z]+/	One or more lowercase letters
/[0-9\.\-]/	Аny number, dot, or minus sign
/^[a-zA-Z0-9_]{1,}$/	Any word of at least one letter, number or _
/([wx])([yz])/	wy, wz, xy, or xz
/[^A-Za-z0-9]/	Any symbol (not a number or a letter)
/([A-Z]{3}|[0-9]{4})/	Three letters or four numbers
/ab*/	An 'a' followed by ZERO or more 'b's
/ab+/	An 'a' followed by ONE or more 'b's
/ab?/	An 'a' followed by zero OR one 'b'
/ab{2}/	An 'a' followed by exactly two b's
/ab{2,}/	An 'a' followed by two or more b's
/a(bc)/	An 'a' followed by zero or one copy of 'bc'
/a(bc)*/	An 'a' followed by zero or more copies of 'bc'
/a(bc){1,5}/	An 'a' followed by one through five copies of 'bc'
/a(bc){*}/	An 'a' followed by zero or more copies of 'bc'
/a.[0-9]/	An 'a' followed by a digit
/[a-d]/	An 'a' followed by lowercase letters 'a' through 'd'
/(a|b)*c/	Has a sequence of a's or b's ending in a c
/(b|cd)ef/	Has either 'aef' or 'cdef' in it
/^.{3}$/	Has exactly 3 characters.
/$|¥[0-9]/	Has a $ or ¥ followed by 0-9
/^[a-zA-Z]/	Starts with any letter.
/[0-9]%/	Single digit before a percent sign.
/,[a-zA-Z0-9]$/	Ends in a comma followed by an alphanumeric character.
/%[^a-zA-Z]%/	Single character that is NOT a letter between two percent signs.
/[\s,]+/	Same as explode on ' ' via preg_split()
/.at/	Three-character string ending with 'at', including 'hat', 'cat', and 'bat'.
/[^b]at/	Same as above except 'bat'.
/[^bc]at/	Same as above except 'bat' and 'cat'.
/^[bc]at/	Allows 'bat' and 'cat', but only at the start of the string.
/[bc]at/$	Allows 'bat' and 'cat', but only at the end of the string.
/\[.\]/	Any single character surrounded by '[' and ']', such as [a], [b].
/a.+c/	Greedy : abcdefghijklmc will return 'abcdefghijklmc'.
/a.*c/	Greedy : abcdefghijklmc will return 'abcdefghijklmc'.
/a.+?c/	Lazy : abcdefghijklmc will return 'abc'.
/a.*?c/	Lazy : abcdefghijklmc will return 'abc'.
/a.+c/U	Lazy : abcdefghijklmc will return 'abc'.
/a.*c/U	Lazy : abcdefghijklmc will return 'abc'.

The standard quantifiers in Regular Expressions are GREEDY, meaning they match as much as they can, only giving back as necessary to match the remainder of the regex. By using a LAZY quantifier, the expression tries the minimal match first.

The LAZY qualifier can be expressed as a "?" inside the pattern OR "U" at the end of the pattern, such as /a.*?c/ and /a.*c/U that produce the same result.

---

CODE FOLLOWS

<?php
include('includes/header.php');

// code
error_reporting(E_ALL);    // set error reporting to all
$self = basename($_SERVER['SCRIPT_NAME']);

echo('<h1>Binita\'s REGEXform</h1>');

$matches[0] = '';
$split[0] = '';

$step = isset($_POST['step']) ? $_POST['step'] : 0;
$pattern = isset($_POST['pattern']) ? $_POST['pattern'] : "/ell/";
$string = isset($_POST['string']) ? $_POST['string'] : "Hello World";
$i = 1;

if($step == 0)     // first time into this form
{
    ?>

    <form action="<?php echo($self); ?>" method="post" >
        <fieldset>
            <legend>REGEX:</legend>
            <label for="pattern">Pattern: &nbsp; </label>
            <input type="text" size="30" id="pattern" name="pattern" value="<?php echo($pattern); ?>">
            <br>
            <label for="string">String: &nbsp; </label>
            <input type="text" size="30" id="string" name="string" value="<?php echo($string); ?>">
        </fieldset>
        <p>
            <input type="hidden" name="step" value="1">
            <input type="submit" name="submit" value="Submit">
        </p>
    </form>

    <table class="full">
        <tr>
            <th>Regular Expression</th>
            <th>Will match...</th>
        </tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/foo/</td>
            <td>The string "foo"</td></tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/^foo/</td>
            <td>'foo' at the start of a string</td></tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/foo$/</td>
            <td>'foo' at the end of a string</td></tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/^foo$/</td>
            <td>'foo' when it is alone on a string</td></tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/[abc]/</td>
            <td>a, b, or c</td></tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/[a-z]/</td>
            <td>Any lowercase letter</td></tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/[^A-Z]/</td>
            <td>Any character that is not a&nbsp;uppercase letter</td></tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/(gif|jpeg)/</td>
            <td>Matches either 'gif' or 'jpeg'</td></tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/[a-z]+/</td>
            <td>One or more lowercase letters</td></tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/[0-9\.\-]/</td>
            <td>Аny number, dot, or minus sign</td></tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/^[a-zA-Z0-9_]{1,}$/</td>
            <td>Any word of at least one letter, number or _</td></tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/([wx])([yz])/</td>
            <td>wy, wz, xy, or xz</td></tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/[^A-Za-z0-9]/</td>
            <td>Any symbol (not a number or a letter)</td></tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/([A-Z]{3}|[0-9]{4})/</td>
            <td>Three letters or four numbers</td>
        </tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/ab*/</td>
            <td >An 'a' followed by ZERO or more 'b's</td>
        </tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/ab+/ </td>
            <td>An 'a' followed by ONE or more 'b's</td>
        </tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/ab?/</td>
            <td> An 'a' followed by zero OR one 'b'</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/ab{2}/ </td>
            <td>An 'a' followed by exactly two b's</td>
        </tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/ab{2,}/</td>
            <td>An 'a' followed by two or more b's</td>
        </tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/a(bc)/ </td>
            <td> An 'a' followed by zero or one copy of 'bc'</td>
        </tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/a(bc)*/</td>
            <td> An 'a' followed by zero or more copies of 'bc'</td>
        </tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/a(bc){1,5}/</td>
            <td> An 'a' followed by one through five copies of 'bc'</td>
        </tr>
        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/a(bc){*}/ </td>
            <td> An 'a' followed by zero or more copies of 'bc'</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/a.[0-9]/ </td>
            <td> An 'a' followed by a digit</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/[a-d]/ </td>
            <td> An 'a' followed by lowercase letters 'a' through 'd'</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/(a|b)*c/</td>
            <td>Has a sequence of  a's or b's ending in a c</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/(b|cd)ef/</td>
            <td> Has either 'aef' or 'cdef' in it</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/^.{3}$/ </td>
            <td> Has exactly 3 characters.</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/$|¥[0-9]/</td>
            <td> Has a $ or ¥ followed by 0-9</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/^[a-zA-Z]/</td>
            <td>Starts with any letter.</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/[0-9]%/ </td>
            <td>Single digit before a percent sign.</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/,[a-zA-Z0-9]$/</td>
            <td>Ends in a comma followed by an alphanumeric character.</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/%[^a-zA-Z]%/ </td>
            <td>Single character that is NOT a letter between two percent signs.</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/[\s,]+/ </td>
            <td>Same as explode on ' ' via preg_split()</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/.at/ </td>
            <td>Three-character string ending with 'at', including 'hat', 'cat', and 'bat'.</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/[^b]at/ </td>
            <td>Same as above except 'bat'.</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/[^bc]at/ </td>
            <td>Same as above except 'bat' and 'cat'. </td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td> /^[bc]at/ </td>
            <td>Allows 'bat' and 'cat', but only at the start of the string.</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/[bc]at/$</td>
            <td>Allows 'bat' and 'cat', but only at the end of the string.</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/\[.\]/ </td>
            <td>Any single character surrounded by '[' and ']', such as [a], [b].</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/a.+c/ </td>
            <td>Greedy : abcdefghijklmc will return 'abcdefghijklmc'.</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/a.*c/ </td>
            <td>Greedy : abcdefghijklmc will return 'abcdefghijklmc'.</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/a.+?c/ </td>
            <td>Lazy : abcdefghijklmc will return 'abc'.</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/a.*?c/ </td>
            <td>Lazy : abcdefghijklmc will return 'abc'.</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/a.+c/U<t/d>
            <td>Lazy : abcdefghijklmc will return 'abc'.</td>
        </tr>

        <tr class="row<?php echo($i++ & 1 );?>">
            <td>/a.*c/U</td>
            <td>Lazy : abcdefghijklmc will return 'abc'.</td>
        </tr>
    </table>

    <p>
        The standard quantifiers in Regular Expressions are GREEDY, meaning they match as much as they can,
        only giving back as necessary to match the remainder of the regex. By using a LAZY quantifier, the
        expression tries the minimal match first.
    </p>

    <p>
        The LAZY qualifier can be expressed as a "?" inside the pattern OR "U" at the end of the pattern, such
        as /a.*?c/ and /a.*c/U that produce the same result.
    </p>

    <?php
}
else
{

    $a = array();

    echo("<p >Pattern: $pattern<br>String: $string</p>");

    // preg_match(string pattern, string string, array matches)

    echo ('<p class="bold">preg_match()</p>');

    if (preg_match($pattern, $string, $matches))
    {
        echo('<pre>');
        print_r( $matches);
        echo('</pre>');
    }
    else
    {
        echo('<pre>');
        print_r( $a);
        echo('</pre>');
    }

    // preg_match_all(string pattern, string string, array matches)

    echo ('<p class="bold">preg_match_all()</p>');

    if (preg_match_all($pattern, $string, $matches))
    {

        echo('<pre>');
        print_r( $matches);
        echo('</pre>');
    }
    else
    {
        echo('<pre>');
        print_r( $a);
        echo('</pre>');
    }

    //    preg_split ( string pattern, string subject [, int limit [, int flags]])

    $split =     preg_split($pattern, $string, PREG_SPLIT_OFFSET_CAPTURE);

    echo ('<p class="bold">preg_split() </p>');
    echo('<pre>');
    print_r( $split);
    echo('</pre>');

    // provide a form to try again
    ?>

    <form action="<?php echo($self); ?>" method="post" >
        <p>
            <input type="hidden" name="pattern" value="<?php echo($pattern);?>">
            <input type="hidden" name="string" value="<?php echo($string);?>">
            <input type="hidden" name="step" value="0">
            <input type="submit" name="submit" value="try Again">
        </p>
    </form>

    <?php
}

include('includes/footer.php');
?>


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