String Operators

There are two string operators. The first is the concatenation operator ('.'), which returns the concatenation of its right and left arguments. The second is the concatenating assignment operator ('.='), which appends the argument on the right side to the argument on the left side. Please read Assignment Operators for more information.


<?php

$a = "Hello ";

$b = $a . "World!"; // now $b contains "Hello World!"



$a = "Hello ";

$a .= "World!";     // now $a contains "Hello World!"

?>

See also the manual sections on the String type and String functions.

User Contributed Notes
String Operators

caliban at darklock dot com
15-Dec-2004 09:57


String concatenation is faster than the array method:



$str="";

$str.="Some string";

$str.="Some other string";

...

$str.="The last string";



That runs roughly twice as fast as:



$str=array();

$str[]="Some string";

$str[]="Some other string";

...

$str[]="The last string";

$str=implode("",$str);



Not that I think this is a terribly widespread practice, but I've got an awful lot of legacy code with this array method in it and a comment to the effect that it's faster than string concatenation. Testing has shown the exact opposite, so I figured I'd enlighten anyone else with this misconception.

anders dot benke at telia dot com
27-Apr-2004 11:53


A word of caution - the dot operator has the same precedence as + and -, which can yield unexpected results. 



Example:



<php

$var = 3;



echo "Result: " . $var + 3;

?>



The above will print out "3" instead of "Result: 6", since first the string "Result3" is created and this is then added to 3 yielding 3, non-empty non-numeric strings being converted to 0.



To print "Result: 6", use parantheses to alter precedence:



<php

$var = 3;



echo "Result: " . ($var + 3); 

?>

php dot net at rinner dot at
19-Feb-2001 07:00


Also see http://www.php.net/manual/en/language.types.string.php for usage of  here doc syntax ("<<<")