I am just beginning to learn PHP and I am using PHP for the Web: Visual Quickstart Guide 4th edition and I have a question about a script I learned in the book and just wrote.
This is the code of the script:
print '<p>Thank you, ' .$title.$name. ' for your comments.</p>
<p>You stated that you found this example to be "'.$response.'" and added:<br />'
.$comments.'</p>';
print "<p>Thank you, $title $name for your comments.</p><p>You stated that you found this example to be '$response' and added:<br/>$comments</p>";
This script is just displaying some data from an HTML form that is pulled via POST.
What is the correct way to do this? I am having a lot of trouble understanding ' vs " in this context.
The second example is the one out of the book and the first example is one that I found how to do after trying to understand the ' vs " question. In regards to this, where is a good location to find information about ' vs ".
Double quoted strings get parsed by the PHP parser for variables and escaped characters like
$x = 10;
echo "$x dollars"; // Outputs: 10 dollars
Single quoted strings do not get parsed so:
$x = 10;
echo '$x dollars'; // Outputs: $x dollars
and to output 10 dollars you would need to do string concatenation:
$x = 10;
echo $x.' dollars';
Parsing variables within strings uses more memory and takes more time than string concatenation. So single quotes are almost always the better way to go. Even though the difference is small.
Double quotes are using to parse variables inside the string. If you use "Hi, $name", it'll correctly parse the variable to, for example, Hi, AlexBeau. If you'd use 'Hi, $name', it'd output Hi, $name.
If you are asking about case where you use . to concatenate strings, it doesn't really matter. Just use it according to rules I mentioned earlier.
Single quotes should be faster though, as there's no parsing going on.
In PHP, variables inside double quoted strings are replaced with their values. This does not happen in single quoted strings.
For example:
$make = 'Nisaan';
$model = 'Altima';
echo 'I drive a $make $model.'; // I drive a $make $model.
echo "I drive a $make $model."; // I drive a Nissan Altima.
You can also use the concatenation operator . to use the value of a variable in a string:
echo 'I drive a '.$make.' '.$model.'.'; // I drive a Nissan Altima.
For more on PHP strings, check the PHP docs: http://php.net/manual/en/language.types.string.php
Where do you see "vs"? It just means "versus" -- compared to.
The difference between the two examples is that the first uses single quotes and string concatenation (adding the strings to each other) and the second uses double quotes and interpolation (getting variables from the environment to insert directly into a single string).