Be careful when using print. Since print is a language construct and not a function, the parentheses around the argument is not required.
In fact, using parentheses can cause confusion with the syntax of a function and SHOULD be omited.
Most would expect the following behavior:
<?php
if (print("foo") && print("bar")) {
// "foo" and "bar" had been printed
}
?>
But since the parenthesis around the argument are not required, they are interpretet as part of the argument.
This means that the argument of the first print is
("foo") && print("bar")
and the argument of the second print is just
("bar")
For the expected behavior of the first example, you need to write:
<?php
if ((print "foo") && (print "bar")) {
// "foo" and "bar" had been printed
}
?>
(PHP 4, PHP 5, PHP 7)
print — Output a string
Descrierea
print
( string
$arg
) : int
Outputs arg.
print is not actually a real function (it is a
language construct) so you are not required to use parentheses
with its argument list.
The major differences to echo are that
print only accepts a single argument and always returns 1.
Parametri
-
arg -
The input data.
Valorile întoarse
Returns 1, always.
Exemple
Example #1 print examples
<?php
print("Hello World");
print "print() also works without parentheses.";
print "This spans
multiple lines. The newlines will be
output as well";
print "This spans\nmultiple lines. The newlines will be\noutput as well.";
print "escaping characters is done \"Like this\".";
// You can use variables inside a print statement
$foo = "foobar";
$bar = "barbaz";
print "foo is $foo"; // foo is foobar
// You can also use arrays
$bar = array("value" => "foo");
print "this is {$bar['value']} !"; // this is foo !
// Using single quotes will print the variable name, not the value
print 'foo is $foo'; // foo is $foo
// If you are not using any other characters, you can just print variables
print $foo; // foobar
print <<<END
This uses the "here document" syntax to output
multiple lines with $variable interpolation. Note
that the here document terminator must appear on a
line with just a semicolon no extra whitespace!
END;
?>
Note
Notă: Deoarece aceasta este o construcție a limbajului și nu o funcție, ea nu poate fi apelată utilizând funcții de operare cu variabile .
A se vedea și
- echo - Output one or more strings
- printf() - Output a formatted string
- flush() - Flush system output buffer
- Heredoc syntax
add a note
User Contributed Notes 3 notes
user at example dot net ¶
16 years ago
danielxmorris @ gmail dotcom ¶
16 years ago
I wrote a println function that determines whether a \n or a <br /> should be appended to the line depending on whether it's being executed in a shell or a browser window. People have probably thought of this before but I thought I'd post it anyway - it may help a couple of people.
<?php
function println ($string_message) {
$_SERVER['SERVER_PROTOCOL'] ? print "$string_message<br />" : print "$string_message\n";
}
?>
Examples:
Running in a browser:
<?php println ("Hello, world!"); ?>
Output: Hello, world!<br />
Running in a shell:
<?php println ("Hello, world!"); ?>
Output: Hello, world!\n
mark at manngo dot net ¶
1 year ago
The other major difference with echo is that print returns a value, even it’s always 1.
That might not look like much, but you can use print in another expression. Here are some examples:
<?php
rand(0,1) ? print 'Hello' : print 'goodbye';
print PHP_EOL;
print 'Hello ' and print 'goodbye';
print PHP_EOL;
rand(0,1) or print 'whatever';
?>
Here’s a more serious example:
<?php
function test() {
return !!rand(0,1);
}
test() or print 'failed';
?>
