arrays - PHP preg_match a specific pattern in hostname -

I have given hostnames and I want to preg_match a specific pattern

hostname :

  sub1.hostname1.com sub12.hostname2.com suboo2.hostname3.com sub2.hostname4.com  after preg_match 

< Strong> desired output :

  sub1.hostname1.com suboo2.hostname3.com sub2.hostname4.com  

This idea received the hostname In which a 1 or 2 in subdomain

If you have a paper and pen, and you have been asked to write a simple algorithm that Does, how do you do it?

How can I do this?

1. You can determine where the sub-domain is, finding the first dot in the string, therefore, Find and then remove subdomain.

2. Since we are only interested in numbers, logically, we will remove whatever we do not.

3. Now we have only one number, and it should be very simple to evaluate whether we want to. In the code, you can do something like this:

     $ samples = ['sub1.hostname1.com', 'sub12. Hostname2.com ',' suboo2.hostname3.com ',' sub2.hostname4.com ',]; Get foreign currency (dollar sample as dollar) {// sub-domain $ dot = strokes ($ domain, '.'); If ($ dot === false) {continue; } $ Sub = substr ($ domain, 0, $ dot); // Remove non-numbers from sub-domain $ number = filter_var ($ sub, FILTER_SANITIZE_NUMBER_INT); // Check what we want if ($ number == 1 or $ number == 2) {resonate "$ domain is a $ number sub-domain & lt; br & gt;"; }}  

   I will leave it as a drill to throw it into a function, if this is what you are looking for.

   If you are completely a regular expression then it will be a matter of examining subdomains for this number:

     foreach ($ samples as $ domain) {$ Matches = preg_match ('/ ^ [^ 0- 9] + (?: 1 | 2) \ ./', $ domain); If ($ matches === 1) {echo "$ domain is domain 1 or 2 subdomain 
   "; }}