检查是否存在具有匹配名称的PDF文件，并链接到该文件

Question

I am working on a real estate website. We are drawing in real estate listings using MLS numbers and some of these listings have PDF brochures. I would like to check if a brochure exists for a listing - the PDF file is "mls#.pdf", with the MLS # matching the listing. If there is a PDF, I want to link to that. Otherwise the link should go to the MLS page for that listing.

I have tried this code below, but I don't know how to set it to search for/link to the filename that matches the listing. (The second echo is clearly wrong too, I don't know how to go back and forth from php in that way).

<?php
$inc_file = "pdf/$MLS_ACCT.pdf";
if (file_exists($inc_file)) {
echo '<a href="pdf/$MLS_ACCT.pdf">Click here for Brochure - Open PDF at 100%</a>';}
else {
echo '<a href="property-search-results.php?MLS_ACCT=<?php echo $MLS_ACCT ;?>" target="_top">Further Details >></a>'; }
?>

Answer 1

Your code that checks whether the file exists looks good. Here's a rundown of how PHP parses variables in strings:

There are several ways to use variables in strings:

$name = "Jeff";

// parsing in double quotes
$string = "My name is $name";

// you can also use curly braces for better readability
$string = "My name is {$name}";

// or you can concatenate
$string = "My name is " . $name;

In single quotes, only the concatenation method works. You should do something like this:

echo '<a href="pdf/' . $MLS_ACCT . '.pdf">Click here for Brochure - Open PDF at 100%</a>';

and you should have the variable printing correctly.

Finally, in your last echo statement, you have <?php ?> in your string. That will print literally - you only use those when you're switching to PHP from pure HTML. Instead, use the same string concatenation method described above.