match user input url to url in php variable

Question

There is a variable

$string = 'http://www.someurl.com/somerandom/page.php';

There is an input

<input type="text" class="theurl" />

I need to verify the first part of the data the user adds to the input matches the first part of the string. Meaning the user data should begin with:

http://www.someurl.com/

But not verify whatever comes after that /, meaning the user can change the

somerandom/page.php

part of things. I am very much still learning php and have come a long way, but this is WAY over my head.

Note I do not want to prefill the data for the user and do not know the variable link ahead of time. I just want to match and verify. Perhaps a mix of jquery/js and php?

I don't even know where to begin. Help? Perhaps example code specific to my issue?

Update / Final

So far here is what i have figured out

$re = "/http:\\/\\/([^\\/\\r\\n]+)/"; 
$string = $baffiliate; 
$newstring = preg_match($re, $string, $matches);
foreach($matches as $key=>$value)
    {
    $value = $value;
    }
if(strpos($_POST['affiliate'], $value) === false) {
echo 'error';
}else{
...do something
}

I opted to use this solution as it didn't require an extra count of thee variable during test :)

Andy Ryu · Accepted Answer · 2016-07-03 07:14:10Z

2

You can use STRPOS.

 $string = 'http://www.someurl.com/somerandom/page.php';
 if(strpos($string, 'http://www.someurl.com/') >= 0) {
    echo 'valid';   
 } else {
    echo 'invalid'; 
 }

answered Jul 3, 2016 at 7:14

Andy Ryu

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jacktheking · Accepted Answer · 2016-07-03 06:25:33Z

0

If you know how long and the exact characters for the first part of the string, you can simply use substr().

$urlLength = 23; // http://www.someurl.com/ have 23 characters
$urlText =  "http://www.someurl.com/"; // What is the text you want to validate?
if (substr($string, 0, $urlLength) == $urlText) {
    echo "Valid.";
}
else {
    echo "Not valid.";
}

The substr() function first take the string ($string). Then if you want the check to start immediately, the second parameter will be '0'. Next is the number of characters you want to validate.

answered Jul 3, 2016 at 6:25

jacktheking

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4 Comments

Bruce Over a year ago

unfortunately, the actual variable link is not known ahead of time. Its entirely retrieved from a database from data input by another user in the system - meaning the url could be any url and any number of characters long.

Bruce Over a year ago

My belief is I am going to have to do some sort of php regex to get all the characters before the 3rd "/" in the url, set those to a variable, do a count on that variable, and then mix your code with that, but regex is so over my head.....

jacktheking Over a year ago

I don't really understand you problem. The code I wrote above do not need you to count for the characters in $string. All you need to do is to provide the first part of the URL you want to validate ("someurl.com/") and then count how long the URl is.

Bruce Over a year ago

Neither answer was right or wrong. As I showed in the final update/code, first I had to use regex to get the URI as the URI is not known. Its a variable passed from the database. After getting the URI through regex, the only way to know how long the URI is, would be to set a variable, and then count the length of the variable srting with strlen. Otherwise how would I know how long the URI is? I selected the answer I did because although it also didn't explain any of the regex part, the last extra strlen count on the string was not required. Both answers would have worked after I did the regex.

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