PHP IV¶

Regex in PHP¶

PHP used to support two regular expression engines
- POSIX
- PCRE
POSIX is deprecated as of PHP 5.3
Because of this, all regular epxression functions you will use start with the prefix preg_
All regex strings need a delimiter inside the quotes
- "/regex/"

Matching¶

PHP has three functions that perform some type of matching
- preg_match(regex,string,[captures]) - Return if the regex is found in the string, optionally capturing groups into provided array
- preg_match_all(regex,string,[captures]) - Finds all matches, storing them in the provided capture variable, and returns the number of matches found
- preg_grep(regex,array) - Returns an array with all elements of the input array that match the regular expression

In [ ]:

$str = <<< END
The phone number for the CSEE Department is 410-455-3500.
The fax number is 410-455-3969.
END;

preg_match("/\d{3}-\d{3}-\d{4}/",$str);

In [ ]:

preg_match("/(\d{3})-(\d{3})-(\d{4})/",$str,$matches);
echo $matches[0];
echo $matches[1];
echo $matches[2];
echo $matches[3];

In [ ]:

preg_match_all("/(\d{3})-(\d{3})-(\d{4})/",$str);

In [ ]:

$n_matches = preg_match_all("/(\d{3})-(\d{3})-(\d{4})/",$str,
        $matches);
for($i = 0; $i < $n_matches; $i++){
    echo $matches[0][$i];
    echo $matches[1][$i];
    echo $matches[2][$i];
    echo $matches[3][$i];
}

In [ ]:

$strs = array('One','Bone','Phone','Tome','Rome');
preg_grep('/one/i',$strs)

In [ ]:

$strs = array('a'=>'One','b'=>'Bone',
              'c' => 'Phone','d' => 'Tome','e' => 'Rome');
preg_grep('/one/i',$strs)

In [ ]:

$strs = array('One','Bone','Phone','Tome','Rome');
preg_grep('/one/i',$strs,PREG_GREP_INVERT)

Regex Practice¶

Find all URLs in a text string and print them

In [ ]:

$text = <<< END
<footer role="contentinfo" id="umbc-footer">

<div id="umbc-footer-logo" class="first-child">[<span class="first-child last-child">UMBC: 
An Honors University in Maryland</span>](https://www.umbc.edu "UMBC: An Honors University in Maryland")</div>

<div id="usmd-footer-logo">[<span class="first-child last-child">Univeristy
System of Maryland</span>](http://www.usmd.edu/ "Univeristy System of Maryland")</div>

<nav id="umbc-footer-nav" style="clear:both;">
    * [About UMBC](https://about.umbc.edu) 
    * [Contact Us](mailto:homepage@umbc.edu)
    * [Equal Opportunity](https://www.umbc.edu/go/equal-opportunity)
    * Community: [<span class="none first-child last-child">Facebook</span>](https://www.facebook.com/umbcpage) 
                 [<span class="none first-child last-child">Twitter</span>](http://twitter.com/umbc) 
                 [<span class="none first-child last-child">YouTube</span>](http://www.youtube.com/user/UMBCtube)
                 [<span class="none first-child last-child">Retriever Net</span>](http://alumni.umbc.edu/)
</nav>

<div id="umbc-footer-info" class="last-child">© University of Maryland, Baltimor
e County <span class="bullet first-child">•</span> 1000 Hilltop C
ircle <span class="bullet last-child">•</span> Baltimore, MD 21250</div>

</footer>
END;

Replacing¶

PHP has several varities of a replace function
The main one is
```
preg_replace(regex,replacement,string)
```
- This replaces all occurences of the pattern in the string with the replacement
- Regex, replacement, and string can all be arrays of strings
There other varities are similar but rather than a replacement string, they take a call back function

In [ ]:

$str = <<< END
Go directly to Jail.
Do not pass Go,
do not collect $200.
END;

$str = preg_replace('/(do not)/i', '<b>$1</b>', $str);
echo $str;

In [ ]:

$chipmunks = array("Alvin","Simon","Theodore");
$chipmunks = preg_replace('/^(.*)$/',"$1 Seville",$chipmunks);
foreach($chipmunks as $chip){
    echo $chip;
}

In [ ]:

$bad_words = array("/Fooey/i", "/Blurgh/i", 
"/Smurf/i", "/Flipping/i");
$str = <<<HERE
Oh fooey, stop saying smurf, we are trying to 
              air this on flipping network tv.
HERE;

preg_replace($bad_words,"*******", $str);

In [ ]:

$bad_words = array("/Fooey/i", "/Blurgh/i",
            "/Smurf/i", "/Flipping/i");
$replacements = array("F***","B****","S***","F*******");
$str = <<<HERE
Oh fooey, stop saying smurf, we are trying to air this on flipping network tv.
HERE;

preg_replace($bad_words,$replacements, $str);

In [ ]:

$lines = file('sherlock.txt');
preg_replace('/Sherlock Holmes/','Bond, James Bond',$lines);

In [ ]:

$lines = file('sherlock.txt');
$names = array('/Sherlock Holmes/','/Henry Baker/', 
              '/Mr[s]\. \w+/');
preg_replace($names,'REDACTED',$lines);

Replacement Practice¶

Replace all social security numbers in text with * for the first 5 numbers, and print the last 4 numberse

In [ ]:

$ssns = <<<END
078-05-1120 is no longer issued because so many people used it as their 
own. Other fake social security numbers include 000-11-1111, and 123-00-1111.
Pretty much any number with all zeros in one location isn't a real number, such
as 1234-56-0000

END;

Quoting¶

The preg_quote(string) function will place a backslash before any special character
This can be useful if you want to do a find operation using user input
- Assuming you want basic find, not regex find

In [ ]:

$string_to_search_for = "The cost of the vase was $100!!";
preg_quote($string_to_search_for);

Globbing¶

Globbing uses shell style regular expressions
- * is all matches, don't need .*
The glob function returns a list of full file names

In [ ]:

glob("/home/bryan/Teaching/CMSC433/*.html")

Sorting¶

PHP has numerous built-in routines to sort arrays, based on
- Ascending or Descending order
- By Key or by Value
- By a user defined functions
All sorts in PHP are done in place

Sorting the Standard Array¶

The two simplest sort functions are
- sort
- rsort
These functions sort an array by value, completely ignoring any key associations that are there

In [ ]:

$number_array = array(6,7,8,4,2,6,7,5,4,3);
sort($number_array);
$number_array;

In [ ]:

$number_array = array(6,7,8,4,2,6,7,5,4,3);
rsort($number_array);
$number_array;

In [ ]:

$string_array = array("asdf","rteu","qerw","vbnm");
sort($string_array);
$string_array;

In [ ]:

$string_array = array("asdf","rteu","qerw","vbnm");
rsort($string_array);
$string_array;

In [ ]:

$assoc_array = array('key1' => 'tiger',
                     'key2' => 'lion', 
                     'k3' => 'cheeta');
sort($assoc_array);
$assoc_array;

In [ ]:

$mixed_array = array(5,6,4,3,1,"asdf","rteu",4,"qerw","vbnm","1");
sort($mixed_array);
$mixed_array;

In [ ]:

$mixed_array = array(5,6,4,3,1,"asdf","rteu",4,"qerw",
                    "vbnm","1");
sort($mixed_array,SORT_STRING);
$mixed_array;

Maintaining Association¶

To sort by value, but keep thet associated keys, use one of the a*sort() functions
- asort()
- arsort()

In [ ]:

$assoc_array = array('key1' => 'tiger',
                    'key2' => 'lion', 
                    'k3' => 'cheeta');
asort($assoc_array);
$assoc_array;

In [ ]:

$assoc_array = array('key1' => 'tiger', 'key2' => 'lion',
                     'k3' => 'cheeta');
arsort($assoc_array);
$assoc_array;

In [ ]:

$number_array = array(6,7,8,4,2,6,7,5,4,3);
asort($number_array);
$number_array;

Sorting by Key¶

To sort by key, use one of the k*sort() functions
- ksort()
- krsort()
There is no aksort() function
- It isn't needed, k*sort() mantains associativity

In [ ]:

$cats = array('asia' => 'tiger', 
              'africa' => 'lion',
              'south_america' => 'jaguar',
              'north_america'=>'bobcat');
ksort($cats);
$cats;

In [ ]:

$cats = array('asia' => 'tiger', 
              'africa' => 'lion',
              'south_america' => 'jaguar',
              'north_america'=>'bobcat');
krsort($cats);
$cats;

In [ ]:

$number_array = array(6,7,8,4,2,6,7,5,4,3);
ksort($number_array);
$number_array;

User-Defined Sort¶

To use a custom sort function, call one of the u*sort functions
- usort()
- uasort()
- uksort()
Each of these functions takes an array and a comparator function

In [ ]:

$semesters = array('Fall 2009','Spring 2010',
                   'Winter 2010','Summer 2010',
                   'Fall 2010');
shuffle($semesters);
$semesters;

In [ ]:

usort($semesters, function($a, $b) {
        $map = array('Winter'=>1, 'Spring'=>2,
                     'Summer'=>3, 'Fall'=>4);
        $aParts = explode(' ', $a);
        $bParts = explode(' ', $b);
        $result = $aParts[1] - $bParts[1];
        return $result == 0 ? $map[$aParts[0]] - $map[$bParts[0]] : $result;
    });
$semesters

In [ ]:

$cats = array('asia' => 'tiger', 
              'africa' => 'lion',
              'south_america' => 'jaguar',
              'north_america'=>'bobcat');
uasort($cats,function($a,$b){
    return strcmp(substr($a,-1),substr($b,-1));
});
$cats;

In [ ]:

$cats = array('asia' => 'tiger', 
              'africa' => 'lion',
              'south_america' => 'jaguar',
              'north_america'=>'bobcat');
uksort($cats,function($a,$b){
    return strlen($b) - strlen($a);
});
$cats;

Sorting Practice¶

Given an array of of associative arrays, each representing facts about a movie, sort by average box office total per day of in theaters
The array looks like this:

In [ ]:

$movies = array('Avengers' => array('box'=> 250000000, 'rating' => 'PG-13', 'days' => 3),
                'I Feel Pretty' => array('box' => 29000000 , 'rating' => 'PG-13', 'days' => 10),
                'Sherlock Gnomes' => array('box' => 40000000, 'rating' => 'PG' , 'days' => 38),
                'Peter Rabbit' => array('box' => 114000000, 'rating' => 'PG', 'days'=>80 ),
                'A Quiet Place' => array('box' => 148173301, 'rating' => 'PG-13', 'days'=>24 ),
                'Black Panther' => array('box' => 688000000, 'rating' => 'PG-13', 'days'=>73 )
                );

Network Access¶

PHP has excellent support for performing operations over a network
Today we will look at two methods
- Accessing content over a network using file IO
- Using the cURL library (almost always isntalled)

Treating a URL like a file name¶

All of PHP's file functions can use a URL inplace of a file name
- You can't write to a URL unless you are using something like FTP and have permission
You must include the scheme so PHP can handle it correctly
- http://
- ftp://
- file://

In [ ]:

$website = file_get_contents("http://umbc.edu");
$website;

In [ ]:

preg_match_all("/<a href=\"(.*?)\">(.*?)<\/a>/",$website,
                $matches);
$matches[1];

In [ ]:

$website_fp = fopen('http://umbc.edu','r');
while($line = fgets($website_fp)){
        echo htmlspecialchars($line);
}

cURL¶

cURl is short for Client URL
The basic use of cURL is the following steps
- Get a curl object using curl_init()
- Set options on the curl object using curl_setopt()
- Execute the curl request using curl_exec()
- Close the curl session using curl_close()

cURL init¶

curl_init can be called in one of two ways
- With no parameters, to create an empty curl object
- With a URL, which is the URL you will be interacting with

cURL Options¶

The main functionaility of cURL are its numerous options which allow you to perform almost any kind of network request
A full list of the predefined constants can be found at http://php.net/manual/en/curl.constants.php
- The ones for setting options start with CURLOPT_

To set an option use

curl_setopt(curl_object, OPTION_CONSTANT, value);

In [ ]:

$ch = curl_init('http://umbc.edu');
$result = curl_exec($ch);
curl_close($ch);

In [ ]:

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://umbc.edu"); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); 
$result =  curl_exec($ch);
curl_close($ch);
$result;

In [ ]:

$lat = 39.2556015207;
$long = -76.71099543;
$radius= 700;
if($radius > 10000){
        $radius = 10000;
}
$curl = curl_init("https://en.wikipedia.org/w/api.php?action=query&prop=coordinates|pageimages|pageterms|info|extracts&colimit=100&piprop=thumbnail&pithumbsize=144&pilimit=50&wbptterms=description&generator=geosearch&ggscoord=${lat}|${long}&ggsradius=${radius}&ggslimit=100&ggsprop=type&format=json&inprop=url");
curl_setopt($curl, CURLOPT_USERAGENT, 'UMBC_CMSC_433_Project/1.0 (https://www.csee.umbc.edu/~bwilk1/433/; bwilk1@umbc.edu)');
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
$data = curl_exec($curl);
echo print_r(json_decode($data),true);
curl_close($curl);

Get Info About Request¶

After executing, you can retrieve additional information from the curl handle
- Headers
- Time information
- IP information
The curl_getinfo function can be passed an curl handle, and optionally flags to denote what info to get
- If no flags are set, all the information is returned

In [ ]:

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "https://umbc.edu"); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); 
$r1 = curl_exec($ch);
$result = curl_getinfo($ch);
curl_close($ch);
$result;