How to change integer value in preg_match PHP? - php

Question

sorry if my question was stupid, please someone help me to fix this issue.
i have string like
$str_value = "http://99.99.99.99/var/test/src/158-of-box.html/9/";
this $str_value is dynamic , it will change each page. now i need to replace 9 in this string as 10. add integer 1 and replace
for example if the $str_value = "http://99.99.99.99/var/test/src/158-of-box.html/251/"
then output should be
http://99.99.99.99/var/test/src/158-of-box.html/252/
i tried to replace using preg_match but i m getting wrong please somesone help me
$str = preg_replace('/[\/\d+\/]/', '10',$str_value );
$str = preg_replace('/[\/\d+\/]/', '[\/\d+\/]+1',$str_value );

Answer 1

Thank's for the answer, #Calimero! You've been faster than me, but I would like to post my answer, too ;-)
Another possibilty is to fetch the integer by using a group. So you don't need to trim $matches[0] to remove the slashes.
$str_value = "http://99.99.99.99/var/test/src/158-of-box.html/9/";
$str = preg_replace_callback('/\/([\d+])\//', function($matches) {
return '/'.($matches[1]+1).'/';
}, $str_value);
echo $str;

Answer 2

You need to use a callback to increment the value, it cannot be done directly in the regular expression itself, like so :
$lnk= "http://99.99.99.99/var/test/src/158-of-box.html/9/";
$lnk= preg_replace_callback("#/\\d+/#",function($matches){return "/".(trim($matches[0],"/")+1)."/";},$lnk); // http://99.99.99.99/var/test/src/158-of-box.html/10/
Basically, the regexp will capture a pure integer number enclosed by slashes, pass it along to the callback function which will purge the integer value, increment it, then return it for replacement with padded slashes on each side.

Answer 3

I'd suggest also another approach based on explode and implode instead of doing any regexp stuff. In my opinion this is more readable.
$str_value = "http://99.99.99.99/var/test/src/158-of-box.html/11/";
// explode the initial value by '/'
$explodedArray = explode('/', $str_value);
// get the position of the page number
$targetIndex = count($explodedArray) - 2;
// increment the value
$explodedArray[$targetIndex]++;
// implode back the original string
$new_str_value = implode('/', $explodedArray);