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Recognizing .pdf and .doc on uploaded files for icons

 
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Recognizing .pdf and .doc on uploaded files for icons
King8654
post 29 Jun, 2008 - 12:48 PM
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Hey

Currently on site, people upload exams to the site, either in doc or pdf. Each has their own icon to show in their description table, which is generated using:

CODE

<?
                  $f=explode(".",$row[3]);
                if($f[1]=="doc")
                {
                    echo "<img src=images/wordlogo.jpg><br>";
                }
                else
                if($f[1]=="pdf")
                {
                       echo "<img src=images/pdflogo.jpg><br>";
                
                                }
          ?>


This works great, UNLESS the uploaded file name has .'s in it like math.final.exam. Math final exam works fine with this code, but the one with .'s in it throws it off, since it looks for the last . and then reads whatever is after it. Is there any way to make this work regardless of whether the user uploads a file with multiple periods in it or not??

Thanks alot
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joeyadms
post 29 Jun, 2008 - 03:01 PM
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what you can do is use substr to read the last 3 letters or better than that grab the extension alltogether like this

CODE

<?php

$str = 'math.final.exam.doc';

$ext = substr($str,strrpos($str,'.')+1);

echo $ext;
?>

this would echo "doc"
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King8654
post 29 Jun, 2008 - 04:19 PM
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Thanks for the response

but the $str will be different for each exam on the site, determined by the link the user clicks on. How can i grab the file name and place it in $str.
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MRJ
post 29 Jun, 2008 - 04:39 PM
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I believe that joeyadms Code is just an example of looking from the right hand side instead of the left so that it should work for any string.
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King8654
post 29 Jun, 2008 - 04:45 PM
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Yes, i understand that it will work with any string, but in the example its math.final.exam, and im asking how to have the string be whatever the exam title is the user clicks on instead of math.final.exam
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joeyadms
post 30 Jun, 2008 - 06:17 AM
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Assuming $row[3] holds the filename, it would look something like this.

CODE

<?php

$fileName = $row[3];
$fileExt = substr($fileName,strrpos($fileName,'.')+1);
if($fileExt == "doc"){
    echo "<img src=images/wordlogo.jpg><br>";
} elseif($fileExt == "pdf"){
    echo "<img src=images/pdflogo.jpg><br>";
}

?>
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kapax
post 2 Jul, 2008 - 05:02 AM
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I see your problem.

I think you may have problems even if you distinguish different extensions. What if user tries to upload a different type of file?

I am not sure about .doc files, but in every .pdf file there is a "%PDF" in the beginning of the source. So, you can easily check whether file is .pdf or not just by opening and checking the first 4 characters.
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joeyadms
post 2 Jul, 2008 - 06:53 AM
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^ All he wants to do is if an uploaded file is pdf show the pdf icon, if it is doc show the doc icon.

The problem he was having was he was looking for the '.' in the file and reading the last letters as the extension, but you can see how a problem would arise if someone uploaded a file called 'something.something.doc' , the script would think 'something.doc' was the extension.

You do not need to descend into the file to solve it, all you need to do is search for the '.' going reverse, starting from the end of the string and moving to the front, that way, no matter what the filename is, you'll always have the extension.
wink2.gif
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girasquid
post 2 Jul, 2008 - 07:04 AM
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Couldn't you do it even simpler by using a regular expression and the $ anchor? Something like this should work, I would think: \.([^.]+)$
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joeyadms
post 2 Jul, 2008 - 01:21 PM
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You pay for regex considerably with performance. The preg* functions are faster these days, but simple searches, like the one here, can be done using strrpos, and substr, they are low cost string manipulations and will work much better than regex.

Using regex you would be doing the same thing with less performance.
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girasquid
post 2 Jul, 2008 - 01:24 PM
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Ah - fair enough, then. I have to say that I don't use PHP much, this just seemed like a spot where regular expressions would fit.
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