One of the hardest things for me to learn is to read error messages and translate them into something meaningful that leads me to a solution. I was excited to read Rachel Andrew’s “A Guide to PHP Error Messages for Designers,” but was a little surprised that some of the most basic ones were left out. So here I’m going to present to you those most common of errors:
1. “Parse error: syntax error, unexpected ‘=’ in errors.php on line 1
Generally this means you used a single “=” to compare two values. E.g. if(1=1){ echo “that”; } In my head when I’m typing out a comparison I say “is equal to” in my head and the “to” reminds me to put down two equals signs. Corny, I know.
2. Parse error: syntax error, unexpected $end in errors.php on line 1
This means you missed closing something before you closed your PHP tag “?>” E.g. <?php if(1==1){ echo “that”; ?> In this case I need to close the if statement before I close php.
3. Notice: Use of undefined constant this – assumed ‘this’ in errors.php on line 1
My code: <?php if(this==’this’){ echo “this equals this”; } ?> Here I forgot the “$” before my variable so PHP is letting me know it interpreted it as a string instead. You’ll actually get the output in this instance because PHP interprets the first value as a string and compares it against an identical string. This can get confusing if–like me–you name variables after the values you expect them to hold.
4. Parse error: syntax error, unexpected T_STRING, expecting ‘,’ or ‘;’ in errors.php on line 1
Generally this means you’ve nested double/single quotes within the same string. In this case, my code looks like: <?php echo “this is a “line” with “multiple” quotes”; ?> To fix this, I can either escape the quotes with a backslash (\”) or change the first and last quotes to single quotes. There is a difference between starting a string with a single or double quote, you can read all about that here.
Along that last line, my new favorite trick is the “heredoc” type string. Often if we have a big chunk of HTML we need to output from PHP we’ll do several lines of something like:
$return = "<p>this is some HTML</p>";
$return .= "<p>my next line of html</p>";
$return .= "<p>another line with a $variable in it</p>";
echo $return;Obviously you can accomplish the same thing from a single line, but when you start to mix in some variables it gets hard to read. You could do the same thing much more simply with heredoc:
$return =<<<EOE
<p>this is some HTML</p>
<p>my next line of html</p>
<p>another line with a $variable in it</p>
EOE;
echo $return;
There are some strict limitations about how to open and close a heredoc so take a good look at the documentation.
I hope this helps anyone struggling to get started with PHP! If you run into an error you can’t explain feel free to post it in the comments.