php regex to change paths - php

Question

I am new to PHP and regex hence need help using it to che some image paths.
My CMS generates image paths like this:
<img src="http://localhost/test/images/normal/ima1.jpg" width="100" height="100" alt="ima1">
I am using PHP and i have a variable $size and I want that if $size = 'small' then the path should be
<img src="http://localhost/test/images/small/ima1.jpg" width="100" height="100" alt="ima1">
and if if $size = 'medium' then the path should be
<img src="http://localhost/test/images/medium/ima1.jpg" width="100" height="100" alt="ima1">
These links are dynamically generated by my CMS hence I am looking for the PHP code which will replace the flder name in these links after the page is rendered.
All I want to replace is the word between images/ and the / after the replacing word.

Answer 1

Try $blabla = preg_replace( "/images\/[a-zA-Z]\//" , "images\/" . $size . "\/" , $sourceCode );
Now, $blabla is a random name. You could change it to whatever you want.
$sourceCode is also a name. You need to replace it with the string you want to replace.
E.g. $sourceCode = "<img src=\"http://localhost/test/images/small/ima1.jpg\" width=\"100\" height=\"100\" alt=\"ima1\">".
The syntax of the function preg_replace is as follows: preg_replace ( mixed $pattern , mixed $replacement , mixed $subject ).
It means: $pattern - the pattern you would like to replace in you string (our case $sourceCode), like "/images\/[a-zA-Z]\//". You could read about regexp syntax here.
$replacement - the text you want to put instead of the pattern. Since we are looking for everything that looks like "images/SOME_TEXT/" - we are replacing the whole pattern. To fill the src attribute correctly, we make our replacement as "image/" . $size . "/".
If we wrote a single $size as the replacement, we would get our $blalba as "<img src=\"http://localhost/test/smallima1.jpg\" width=\"100\" height=\"100\" alt=\"ima1\">".
Notice the smallima1.jpg (that's in case $size = "small").
P.S. Notice the backslashes before every ". They are preventing from the php parser to think it's the end of the string input. E.g. $name = "The "Batman""; will return error, while $name = "The \"Batman\""; will assign The "Batman" to the variable $name.
They are neccessary, if you assign a string that contains quotes to a variable.

Answer 2

My question for you is why do you want to replace ??? I if your site is properly structured you don't need replace
I expect something like this
$sizes = array("normal"=>array(500,500),
"small"=>array(100,100),
"medium"=>array(300,200));
$selected = "small" ;
$imageHost= "http://localhost/test/images" ;
$imagePath = "/public_html/test/images" ;
$imageName = "ima1.jpg" ;
$tag = "<img src=\"{$imageHost}/%s/$imageName\" width=\"%d\" height=\"%s\" alt=\"ima1\">";
Simple Demo to output all sizes
echo "<pre>" ;
foreach($sizes as $size => $dim){
if(!file_exists($imagePath . DIRECTORY_SEPARATOR . $selected . DIRECTORY_SEPARATOR . $imageName))
{
// Am sure you want to either create the image or copu the thumn here
}
echo printf($tag,$size,$dim[0],$dim[1]) . PHP_EOL;
}
Output
<img src="http://localhost/test/images/normal/ima1.jpg" width="500" height="500" alt="ima1">
<img src="http://localhost/test/images/small/ima1.jpg" width="100" height="100" alt="ima1">
<img src="http://localhost/test/images/medium/ima1.jpg" width="300" height="200" alt="ima1">

Answer 3

Providing that all your images are under the same path, I recommend you leave regular expressions alone (this time), and opt for a much easier explode() method.
Using the PHP explode() function you can split a string into an array using a delimiter.
$str = 'http://localhost/test/images/small/ima1.jpg';
$arr = explode('/',$str);
This should give you something like this -
Array
(
[0] => http:
[1] =>
[2] => localhost
[3] => test
[4] => images
[5] => small
[6] => ima1.jpg
)
// remove the protocol specification and the empty element.
// You'll see that the `explode()` function actually removes the slashes
// (including the two at the beginning of the URL in the protocol specification),
// you'll have to return them once you have finished.
array_shift($arr);
array_shift($arr);
Now you are left with -
Array
(
[0] => localhost
[1] => test
[2] => images
[3] => small
[4] => ima1.jpg
)
Providing the URL's are the same for all images, you can simply replace the fourth element ($arr[3]) with the relevant size and then reassemble your URL using the implode() function.
array_unshift($arr,'/'); // adds an element to the beginning of an array
array_unshift($arr,'http:');
$finalURL = implode('/',$arr);
Relevant documentation -
explode() - http://www.php.net/manual/en/function.explode.php
implode() - http://php.net/manual/en/function.implode.php
array_shift() - http://php.net/manual/en/function.array-shift.php
array_unshift() - http://www.php.net/manual/en/function.array-unshift.php