Strings

Strings can be specified using one of two sets of delimiters.

If the string is enclosed in double-quotes ("), variables within the string will be expanded (subject to some parsing limitations). As in C and Perl, the backslash ("\") character can be used in specifying special characters:

If you attempt to escape any other character, both the backslash and the character will be output. In PHP 3, a warning will be issued at the E_NOTICE level when this happens. In PHP 4, no warning is generated.

The second way to delimit a string uses the single-quote ("'") character. When a string is enclosed in single quotes, the only escapes that will be understood are "\\" and "\'". This is for convenience, so that you can have single-quotes and backslashes in a single-quoted string. Variables will not be expanded inside a single-quoted string.

Another way to delimit strings is by using here doc syntax ("<<<"). One should provide an identifier after <<<, then the string, and then the same identifier to close the quotation.

The closing identifier must begin in the first column of the line. Also, the identifier used must follow the same naming rules as any other label in PHP: it must contain only alphanumeric characters and underscores, and must start with a non-digit character or underscore.

Here doc text behaves just like a double-quoted string, without the double-quotes. This means that you do not need to escape quotes in your here docs, but you can still use the escape codes listed above. Variables are expanded, but the same care must be taken when expressing complex variables inside a here doc as with strings.

Example 6-2. Here doc string quoting example <?php $str = <<<EOD Example of string spanning multiple lines using heredoc syntax. EOD; /* More complex example, with variables. */ class foo { var $foo; var $bar; function foo() { $this->foo = 'Foo'; $this->bar = array('Bar1', 'Bar2', 'Bar3'); } } $foo = new foo(); $name = 'MyName'; echo <<<EOT My name is "$name". I am printing some $foo->foo. Now, I am printing some {$foo->bar[1]}. This should print a capital 'A': \x41 EOT; ?>

Strings may be concatenated using the '.' (dot) operator. Note that the '+' (addition) operator will not work for this. Please see String operators for more information.

Characters within strings may be accessed by treating the string as a numerically-indexed array of characters, using C-like syntax. See below for examples.

Example 6-3. Some string examples <?php /* Assigning a string. */ $str = "This is a string"; /* Appending to it. */ $str = $str . " with some more text"; /* Another way to append, includes an escaped newline. */ $str .= " and a newline at the end.\n"; /* This string will end up being '<p>Number: 9</p>' */ $num = 9; $str = "<p>Number: $num</p>"; /* This one will be '<p>Number: $num</p>' */ $num = 9; $str = '<p>Number: $num</p>'; /* Get the first character of a string */ $str = 'This is a test.'; $first = $str[0]; /* Get the last character of a string. */ $str = 'This is still a test.'; $last = $str[strlen($str)-1]; ?>

 $beer = 'Heineken';
 echo "$beer's taste is great"; // works, "'" is an invalid character for varnames
 echo "He drunk some $beers"; // won't work, 's' is a valid character for varnames
 echo "He drunk some ${beer}s"; // works
       

 $fruits = array( 'strawberry' => 'red' , 'banana' => 'yellow' );
 echo "A banana is $fruits[banana].";
 echo "This square is $square->width meters broad.";
 echo "This square is $square->width00 centimeters broad."; // won't work,
    // for a solution, see the complex syntax.
 
 
 
       

 $great = 'fantastic';
 echo "This is { $great}"; // won't work, outputs: This is { fantastic}
 echo "This is {$great}";  // works, outputs: This is fantastic
 echo "This square is {$square->width}00 centimeters broad."; 
 echo "This works: {$arr[4][3]}";     
 echo "This is wrong: {$arr[foo][3]}"; // for the same reason 
    // as $foo[bar] is wrong outside a string. 
 
 echo "You should do it this way: {$arr['foo'][3]}";
 echo "You can even write {$obj->values[3]->name}";
 echo "This is the value of the var named $name: {${$name}}";
 
 
 // this works, but i disencourage its use, since this is NOT 
 // involving functions, rather than mere variables, arrays and objects.
 $beer = 'Heineken';
 echo "I'd like to have another {${ strrev('reeb') }}, hips";
 
 
       

$foo = 1 + "10.5";              // $foo is float (11.5)
$foo = 1 + "-1.3e3";            // $foo is float (-1299)
$foo = 1 + "bob-1.3e3";         // $foo is integer (1)
$foo = 1 + "bob3";              // $foo is integer (1)
$foo = 1 + "10 Small Pigs";     // $foo is integer (11)
$foo = 1 + "10 Little Piggies"; // $foo is integer (11)
$foo = "10.0 pigs " + 1;        // $foo is integer (11)
$foo = "10.0 pigs " + 1.0;      // $foo is float (11)     
     

echo "\$foo==$foo; type is " . gettype ($foo) . "<br>\n";