Comments in the Book
Further in the book, I will sometimes comment on the result of code execution. For example, like this:
<?php
echo 'hello'; // will output 'hello'
?>
As you can see, I put the output result in quotes in the comment. However, this string will be displayed on the screen without quotes. I specified them to emphasize that we are outputting exactly a string.
If we output a number, I will not put it in quotes:
<?php
echo 12345; // will output 12345
?>
This distinction is necessary because we can also output a string with digits to the screen:
<?php
echo '12345'; // will output '12345'
?>
Technically, it will be sent to the browser the same way. But in PHP, there is a difference between numbers and strings with digits, so I will always emphasize it.