[RESOLVED] Need help displaying text between 2 markers.

pearjam

Howdy again!

I'm wanting to display, on a different page - text between two markers in a file.

So on Page A there's text like:

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Quisque sapien ipsum. <tag>Ornare sed aliquet at, pharetra vel mauris.<tag> Morbi ut tortor ligula, a tempus lorem.

On Page B, I'd like to display just the text between the <tag> markers.

How can this be done with very little php (efficiently)? 🙂

Would it work like - php gets file abcd.php - finds <tag> - echo's text - stops echoing at the next <tag>?

bpat1434

You could use [man]strpos/man to find the first occurrence of the string, then use strpos() again to find the next occurrence after the first. Then use [man]substr/man to cut out that section.

Something like:

$string = file_get_contents($fileA);
$start = strpos($string, '<tag>', 0);
$ends = strpos($string, '<tag>', $start+5);

echo substr($string, $start+5, $ends);

The other alternative is to use a regular expression to do relatively the same thing.

$string = file_get_contents($fileA);

preg_match('~<tag>(.*)<tag>~iUs', $string, $matches);
echo $matches[1];

pearjam

Hey, that worked!! Thank you!!

I chose option 2, and changed this:

$string = file_get_contents('./oldfile.php');

Awesome! That got me looking at the manual for "file_get_contents" and I noticed you could use $maxlen to tell it when to stop reading...

The file's going to get bigger, so I thought I could try specifying the top half the file (where the <tag>s are at) -- but it's not working.

Any ideas on how I could add that? Maybe even have it see the EOF as right after the last <tag>?

bpat1434

The problem with using file_get_contents is that it has to read the full file before you can do anything with it. If you wanted to look for "<tag>" while you read teh contents, you'd need to use [man]fopen/man with [man]fread/man to read chunks of a file. You can then search the new chunk to see if it has the second instance of your tag.

pearjam

I'm interested in what your saying, but I have no idea how to implement it.

You mean I could only read one section of the file, and display that?

Kudose

Read the documentation on the links bpat provided. Generally one character is equal to one byte ... so supplying 100 to [man]fread[/man] will read in 100 characters/bytes, which you can use before reading the next 100 characters.

pearjam

Gotcha...

Ok, I'm a novice (look at how many posts I've made compared to you guys). I didn't see that bpat had posted links... 🙁

How would the syntax be to use fopen and fread?

I'm guessing php would use fopen to open the file, then fread [100 bytes], but how to select the info between the <tags>?

(sorry guys for so many questions on syntax stuff)

Kudose

It's alright (I didn't mean to insult you), the blue underlined words are links, usually to the manual when intermixed in a paragraph.

Please refer to [man]fread[/man] on how to use the function in conjuction with [man]fopen[/man].

In regards to the <tags> tag, [man]fgets[/man] may be better for you since it reads in a line from a file. You could use it to get a line and check if the line equals <tag>. The read in all lines until you match a line with </tag>.

pearjam

So here's what I was able to put together from the manual...

<?php
$string = fopen('./oldfile.php', 'r');
fgets($string, '~<tag>(.*)<tag>~iUs', $matches);
echo $matches[1];
?>

....and it's not working. lol

Kudose

What manual are you reading?

There are not 3 parameters to [man]fgets[/man].

Coping from example #1 on [man]fgets[/man]

<?php
$handle = @fopen("/tmp/inputfile.txt", "r");
if ($handle) {
    while (!feof($handle)) {
        $buffer = fgets($handle, 4096);
        echo $buffer;
    }
    fclose($handle);
}
?>

You could do something like

<?php
$handle = @fopen("./oldfile.php", "r");
if ($handle) {
    while (!feof($handle)) {
        $buffer = fgets($handle, 4096);
        if($buffer == '<tag>'){
          // do something
        }
    }
    fclose($handle);
}
?>

Also, using fopen to open a .php file is generally not a good idea. Use .dat or .txt files.

pearjam

Well, that's the thing - how does

if($buffer == '<tag>'){

..get the content between the <tag> tags?

(that's why I was trying to blend the first example from bpat, but I'm wanting to not read the whole file if possible.)

Kudose

It doesn't get it ... like I said before it reads each line and it is up to you to match it and process from there.

pearjam

I guess I don't get it either...

Thank you for trying to help though.

bpat1434

Pearjam, here's a quick example.

$fileA = '/path/to/somefile.txt';

// Open the file for reading
$fp = fopen($fileA, 'r');

$data = '';
$opened = false;
$done = false;

// While we're not reading the end of the file
while(!feof($fp))
{
    // If we're done, break out of this loop
    if($done === true)
    {
        break;
    }

// Read the next 8192 bytes, the most memory efficient way
// since it's the smallest chunk size
$next = fread($fp, 8192);

// If we still have yet to find the "opening" tag
if(!$opened)
{
    // Look for it in the next line of code
    $open = strpos($next, '<tag>');

    // If the opening tag was found, store from that point forward
    if($open !== false)
    {
        $data = substr($next, $open);
        // Set that we found the opening tag
        $opened = true;
    }
}
// Otherwise, we've found the opening tag, just need to locate the closing one
else
{
    // Search for the closing tag within the next line(s)
    $close = strpos($next, '<tag>');

    // If we've found it, then store up to that point
    if($close !== false)
    {
        $data .= substr($next, 0, $close);
        $done = true;
    }
    // Otherwise, just add the line to our data
    else
    {
        $data .= $next;
    }
}
}

// Close the file handler
fclose($fp);

// Echo out the results
echo $data;

pearjam

bpat1434

That's an awesome example - but I'm having a hard time making it work.

The very first example you showed me however works like a charm.

I was worried that the file it was reading would become to large, then I realized that half of the file was markup.

I moved the info to a flat file, so there's nothing there but the content it needs to read. So - it's dynamically efficient!

Thank you for your help again 🙂 , your first example is the one I'm going with!