PHP Strings
PHP Strings
A string is a sequence of characters, like "Hello world!".
In PHP, strings are surrounded by either double quotes, or single quotes.
Note: There is a difference between double quotes and single quotes in PHP.
Double or Single Quotes?
You can use double or single quotes, but you should be aware of the differences between the two.
A double quoted string will substitute the value of variables, and accepts many special characters, like \n, \r, \t by escaping them.
Example
A double quoted string will substitute the value of variables:
$x = "John";
echo "Hello $x"; // Returns Hello John
A single quoted string does not substitute the value of variables, and will output the string as it was written:
Example
A single quoted string outputs the string as it is:
$x = "John";
echo 'Hello $x'; // Returns Hello $x
Differences between Single and Double Quotes
| Feature | Single Quotes | Double Quotes |
|---|---|---|
| Variable interpolation | No - variables like $x are output literally | Yes - variables are replaced with their values |
| Escape sequences | Only \' and \\ are supported | Supports many, like: \n, \t, \r, \$, \" |
| Performance | Slightly faster (PHP does not need to parse the content) | Slightly slower (PHP must scan for variables and escape sequences) |
| Readability | Cleaner for simple, constant strings | More readable for strings with many variables (do not need to use the concatenation operator (.)) |
Example
See some differences beween double and single quotes:
// Using double quotes
$x = "John";
echo "Hello $x\n";
echo "\tHow are you?\n";
// Using single quotes
$x = 'John';
echo 'Hello $x\n';
echo '\tHow are you?\n';Complete PHP String Reference
For a complete reference of all string functions, go to our complete PHP String Reference.
