(PHP 4, PHP 5, PHP 7, PHP 8)
echo — Output one or more strings
...$expressions
): voidOutputs one or more expressions, with no additional newlines or spaces.
echo
is not a function but a language construct.
Its arguments are a list of expressions following the echo
keyword, separated by commas, and not delimited by parentheses.
Unlike some other language constructs, echo
does not have
any return value, so it cannot be used in the context of an expression.
echo
also has a shortcut syntax, where you can
immediately follow the opening tag with an equals sign. This syntax is available
even with the short_open_tag configuration
setting disabled.
I have <?=$foo?> foo.
The major differences to print are that
echo
accepts multiple arguments and doesn't have a return value.
expressions
One or more string expressions to output, separated by commas.
Non-string values will be coerced to strings, even when
the
strict_types
directive is enabled.
No value is returned.
Example #1 echo
examples
<?phpecho "echo does not require parentheses.";// Strings can either be passed individually as multiple arguments or// concatenated together and passed as a single argumentecho 'This ', 'string ', 'was ', 'made ', 'with multiple parameters.', "\n";echo 'This ' . 'string ' . 'was ' . 'made ' . 'with concatenation.' . "\n";// No newline or space is added; the below outputs "helloworld" all on one lineecho "hello";echo "world";// Same as aboveecho "hello", "world";echo "This string spansmultiple lines. The newlines will beoutput as well";echo "This string spans\nmultiple lines. The newlines will be\noutput as well.";// The argument can be any expression which produces a string$foo = "example";echo "foo is $foo"; // foo is example$fruits = ["lemon", "orange", "banana"];echo implode(" and ", $fruits); // lemon and orange and banana// Non-string expressions are coerced to string, even if declare(strict_types=1) is usedecho 6 * 7; // 42// Because echo does not behave as an expression, the following code is invalid.($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 is a valid expression, returning 1, // so it may be used in this context.echo $some_var ? 'true': 'false'; // evaluating the expression first and passing it to echo?>
Note: Because this is a language construct and not a function, it cannot be called using variable functions, or named arguments.
Note: Using with parentheses
Surrounding a single argument to
echo
with parentheses will not raise a syntax error, and produces syntax which looks like a normal function call. However, this can be misleading, because the parentheses are actually part of the expression being output, not part of theecho
syntax itself.
<?phpecho "hello";// outputs "hello"echo("hello");// also outputs "hello", because ("hello") is a valid expressionecho(1 + 2) * 3;// outputs "9"; the parentheses cause 1+2 to be evaluated first, then 3*3// the echo statement sees the whole expression as one argumentecho "hello", " world";// outputs "hello world"echo("hello"), (" world");// outputs "hello world"; the parentheses are part of each expressionecho("hello", " world");// Throws a Parse Error because ("hello", " world") is not a valid expression?>
Passing multiple arguments to echo
can avoid
complications arising from the precedence of the concatenation operator in
PHP. For instance, the concatenation operator has higher precedence than
the ternary operator, and prior to PHP 8.0.0 had the same precedence as addition
and subtraction:
<?php// Below, the expression 'Hello ' . isset($name) is evaluated first,// and is always true, so the argument to echo is always $nameecho 'Hello ' . isset($name) ? $name : 'John Doe' . '!';// The intended behaviour requires additional parenthesesecho 'Hello ' . (isset($name) ? $name : 'John Doe') . '!';// In PHP prior to 8.0.0, the below outputs "2", rather than "Sum: 3"echo 'Sum: ' . 1 + 2;// Again, adding parentheses ensures the intended order of evaluationecho 'Sum: ' . (1 + 2);
If multiple arguments are passed in, then parentheses will not be required to enforce precedence, because each expression is separate:
<?phpecho "Hello ", isset($name) ? $name : "John Doe", "!";echo "Sum: ", 1 + 2;