How to find the second string between two strings

Question

I have been working on a script that pulls information from a certain website. The said website pulls the information from a database and displays it in a way the user can easily read it (like always).

Imagine it looks like this:

Var1: result1 Var2: result2 Var3: result3

What my script does is that it reads the page's source code and retrieves "result1", "result2" and "result3" by obtaining the text between two strings.

Sample code:

<?php

    function get_string_between($string, $start, $end) {

        $string = " ".$string;
        $ini = strpos($string,$start);
        if ($ini == 0) return "";
        $ini += strlen($start);
        $len = strpos($string,$end,$ini) - $ini;
        return substr($string,$ini,$len);

    }

    function check($url) {

        // usually, $fullstring = file_get_contents($url);
        $fullstring = "<string1>result1</string1><string1>result2</string1><string1>result3</string1>";

        $result = get_string_between($fullstring, "<string1>", "</string1>");

        echo "<b>Result: </b>".$result;

    }

    check("random");    // just to execute the function

?>

In case you wonder why I have the check() function there it is because this code is part of something bigger and I need a solution that works in this case scenario, so I tried to keep it immaculate.

Now, I can easily get "result1" because it's the first occurrence, but how can I get "result2" and "result3"?

Thank you :)

I had to re-read the code a few times, but I understand what you're trying to do here. — Matt
– Matt, Commented Aug 7, 2012 at 18:40
@Matt I found the sample very helpful, it represents another way to do this and it is definitely a relevant example for this situation. The problem is that I don't know exactly how many occurrences of the string I will be dealing with and what the strings will look like(I should have stated this in the original question). In case I am misunderstanding the code, doesn't it retrieve the position of a certain string(that you define)? — user1298923
– user1298923, Commented Aug 7, 2012 at 18:49
Check out @nickb's answer. That will get you what you need. If you return the entire array of matches that his code gives you, you can then iterate through it using a foreach. — Matt
– Matt, Commented Aug 7, 2012 at 18:52

nickb · Accepted Answer · 2012-08-07 18:39:31Z

3

Use a regex to extract all of the matches, then pick the ones you want:

function get_string_between($string, $start, $end) 
{
    preg_match_all( '/' . preg_quote( $start, '/') . '(.*?)' . preg_quote( $end, '/') . '/', $string, $matches);
    return $matches[1];
}

The regex will capture anything between the $start and $end variables.

Now the function returns an array of all of the result values, which you can pick which one you want:

list( $first, $second, $third) = get_string_between( $string,  "<string1>", "</string1>");

You can see it working in this demo.

answered Aug 7, 2012 at 18:39

nickb

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6 Comments

Matt Over a year ago

Take it a step further and you can add $matches as a reference parameter function get_string_between($string, $start, $end, &$matches) {...}

user1298923 Over a year ago

Thanks for your answer, I have two questions. 1) What can I do if I don't know the number of occurrences (i can have 1,2,3,4,5..200 times <string1>text</string1>) and 2) How can I retrieve ONLY "result1" instead of "string 'result1' (length=7)"? Thanks again

Matt Over a year ago

Or you can return $matches and the programmer can then process it as an array instead of just a string.

nickb Over a year ago

This returns an array - It'll work with any number of occurrences. Your second question is trivial and shows a lack of understanding of the language - The output you're seeing is from var_dump() to show you the type of the variable. If you just did echo $first; on my demo, you wouldn't get var_dump()'s output.

user1298923 Over a year ago

@nickb Yes, I do lack knowledge when it comes to php and I realise it shows, that is probably the reason why I will be asking the following question, one that looks basic to you: How can I make it work with a random number of occurrences? In your example you set $list( $first, $second, $third), implying we only have three occurrences.

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