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echo

(PHP 4, PHP 5, PHP 7)

echoOutput one or more strings

Description

echo ( string $arg1 [, string $... ] ) : 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 with it. 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 short_open_tag configuration setting enabled.

I have <?=$foo?> foo.

The major differences to print are that echo accepts an argument list and doesn't have a return value.

Parameters

arg1

The parameter to output.

...

Return Values

No value is returned.

Examples

Example #1 echo examples

<?php
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
?>

Notes

Note: Because this is a language construct and not a function, it cannot be called using variable functions.

Tip

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:

<?php
echo "Sum: "2;
echo 
"Hello ", isset($name) ? $name "John Doe""!";

With concatenation, the period operator has a higher precedence than both the addition and ternary operators, and so parentheses must be used for the correct behaviour:

<?php
echo 'Sum: ' . (2);
echo 
'Hello ' . (isset($name) ? $name 'John Doe') . '!';

See Also

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User Contributed Notes 1 note

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28
pemapmodder1970 at gmail dot com
2 years ago
Passing multiple parameters to echo using commas (',')is not exactly identical to using the concatenation operator ('.'). There are two notable differences.

First, concatenation operators have much higher precedence. Referring to http://php.net/operators.precedence, there are many operators with lower precedence than concatenation, so it is a good idea to use the multi-argument form instead of passing concatenated strings.

<?php
echo "The sum is " . 1 | 2; // output: "2". Parentheses needed.
echo "The sum is ", 1 | 2; // output: "The sum is 3". Fine.
?>

Second, a slightly confusing phenomenon is that unlike passing arguments to functions, the values are evaluated one by one.

<?php
function f($arg){
 
var_dump($arg);
  return
$arg;
}
echo
"Foo" . f("bar") . "Foo";
echo
"\n\n";
echo
"Foo", f("bar"), "Foo";
?>

The output would be:
string(3) "bar"FoobarFoo

Foostring(3) "bar"
barFoo

It would become a confusing bug for a script that uses blocking functions like sleep() as parameters:

<?php
while(true){
  echo
"Loop start!\n", sleep(1);
}
?>

vs

<?php
while(true){
  echo
"Loop started!\n" . sleep(1);
}
?>

With ',' the cursor stops at the beginning every newline, while with '.' the cursor stops after the 0 in the beginning every line (because sleep() returns 0).
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