Question

Yes as the title says:

How can i detect an file extension? $_POST[‘fname’]; is where i have the filename stored e.g asddsa.jpg

So how can i check if .jpg then … if .png then … ?

    $src = "images/status/photo/".$_POST['fname'];
    $parts=pathinfo($src);
if($parts['extension'] == "jpg"){
    $img_r = imagecreatefromjpeg($src);
}elseif($parts['extension'] == "png"){
    $img_r = imagecreatefrompng($src);
}elseif($parts['extension'] == "gif"){
    $img_r = imagecreatefromgif($src);
}

tried this too without any success:

    $ext= pathinfo($src, PATHINFO_EXTENSION);
if($ext == "jpg"){
    $img_r = imagecreatefromjpeg($src);
}elseif($ext == "png"){
    $img_r = imagecreatefrompng($src);
}elseif($ext == "gif"){
    $img_r = imagecreatefromgif($src);
}

Answer 1

The proper way to do this would be to use pathinfo on the file. For example…

$parts=pathinfo('somefile.jpg');
echo $parts['extension']; //Returns "jpg"

Now, you’re simply looking at a string in a variable, so the way to handle this would be something like this…

$parts=explode(".", $_POST['fname']);
echo $parts[count($parts)-1];

Finally, you should not be detecting file type by extension. This is bad. Instead, you should be using the content-type (commonly referred to as MIME type). You can find this in $_FILES['userfile']['type'] for uploaded files. (documentation)

Once you have your type, you can do a simple switch statement.

Also, beware of folks uploading content that isn’t what it says it is. Someone can send files to you with a specific content type, but it may be something such as executable code instead! The only way to be sure is to check the files with your own code server-side. Never trust user input.