What difference does it makes when I use '' against "" ?

Question

What difference does it makes when I use '' against "" ?

For example:

$example = 'Merry Christmas in Advance';
$eg = "Merry Christmas";

echo "$example";
echo '$example';


echo "$eg";
echo '$eg';

What would the output for each echo statements and what can we infer about '' vs "" in PHP ?

Answer 1

Single-quoted variables take input literally, double-quotes interpret escape sequences for special chars and expand variables.

You can see some good examples here: http://php.net/manual/en/language.types.string.php

Note that SOME escape sequences are still interpreted within single quotes. Example:

// Outputs: Arnold once said: "I'll be back"

echo 'Arnold once said: "I\'ll be back"';

Answer 2

Double quotes interpolate variables.

Answer 3

You can also include variables inside double quotes and those will be interpreted as variables, rather than strings

So:

$variable = 1;
echo 'this $variable' ==> will output 'this $variable'
echo "this $variable" ==> will output 'this 1'

Answer 4

$example = 'Merry Christmas in Advance';
$eg = "Merry Christmas";

echo "$example";
echo '$example';

echo "$eg";
echo '$eg';

would produce:

Merry Christmas in Advance$exampleMerry Christmas$eg

Single quoted strings are handled literally. No special characters (such as \n) or variables are interpolated.

Double quoted strings will interpolate your variables and special characters and render them accordingly.