(PHP 4, PHP 5, PHP 7)
echo — Output one or more strings
$...] ) : void
Outputs all parameters. No additional newline is appended.
echo is not actually a function (it is a
language construct), so you are not required to use parentheses
echo (unlike some other language
constructs) does not behave like a function, so it cannot
always be used in the context of a function. Additionally, if you want to
pass more than one parameter to
echo, the parameters
must not be enclosed within parentheses.
echo also has a shortcut syntax, where you can
immediately follow the opening tag with an equals sign. Prior to PHP 5.4.0,
this short syntax only works with the
I have <?=$foo?> foo.
The major differences to
echo accepts an argument list and doesn't have a return value.
The parameter to output.
No value is returned.
echo "Hello World";
// Strings can either be passed individually as multiple arguments or
// concatenated together and passed as a single argument
echo 'This ', 'string ', 'was ', 'made ', 'with multiple parameters.', chr(10);
echo 'This ' . 'string ' . 'was ' . 'made ' . 'with concatenation.' . "\n";
// Because echo does not behave like a function, the following code is invalid.
($some_var) ? echo 'true' : echo 'false';
// However, the following examples will work:
($some_var) ? print 'true' : print 'false'; // print is also a construct, but
// it behaves like a function, so
// it may be used in this context.
echo $some_var ? 'true': 'false'; // changing the statement around
Note: Because this is a language construct and not a function, it cannot be called using variable functions.
A benefit to passing in multiple arguments over using concatenation in echo regards the precedence of the period operator in PHP. If multiple arguments are passed in, then parentheses will not be required to enforce precedence:
echo "Sum: ", 1 + 2;
echo "Hello ", isset($name) ? $name : "John Doe", "!";
With concatenation, the period operator has the same precedence as the addition operator, and higher precedence than the ternary operator, so parentheses must be used for the correct behaviour:
echo 'Sum: ' . (1 + 2);
echo 'Hello ' . (isset($name) ? $name : 'John Doe') . '!';