If (preg_match ('/\ D/', $ page)

If (preg_match ('/\ D/', $ page) what does it mean if (preg_match ('/\ D/', $ page) {$ this-& gt; page = 1 ;}else {$ this-& gt; page = $ page ;}, paging? If the page number ($ page) contains a non-number, if (preg_match ('/\ D/', $ page), what does it mean?
If (preg_match ('/\ D/', $ page ))

{$ This-> page = 1;
}
Else {
$ This-> page = $ page;
}


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Paging?
If a non-number exists in the page number ($ page), set the page number to 1.

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Regular expression, matching $ page whether it contains digits
If no number exists, $ this-> page = 1;
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If condition preg_match ('/\ D/', $ page) is a regular match
Match non-numeric content on $ page. \ d is a number \ D is not a number
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Regular Expression Matching: matches non-numeric content on $ page. \ d is a number. \ w represents uppercase and lowercase letters, numbers, and underscores, \ W indicates the opposite of \ w, and so on!