Strings
PHP Manual

echo

(PHP 4, PHP 5)

echo — Output one or more strings

说明

void echo ( string $arg1 [, string $... ] )

Outputs all parameters.

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. This short syntax only works with the short_open_tag configuration setting enabled.

I have <?=$foo?> foo.

参数

arg1

The parameter to output.

...

返回值

无返回值。

范例

Example#1 echo() examples

<?php
echo "Hello World";

echo 
"This spans
multiple lines. The newlines will be
output as well"
;

echo 
"This spans\nmultiple lines. The newlines will be\noutput as well.";

echo 
"Escaping characters is done \"Like this\".";

// You can use variables inside of an echo statement
$foo "foobar";
$bar "barbaz";

echo 
"foo is $foo"// foo is foobar

// You can also use arrays
$baz = array("value" => "foo");

echo 
"this is {$baz['value']} !"// this is foo !

// Using single quotes will print the variable name, not the value
echo 'foo is $foo'// foo is $foo

// If you are not using any other characters, you can just echo variables
echo $foo;          // foobar
echo $foo,$bar;     // foobarbarbaz

// Some people prefer passing multiple parameters to echo over concatenation.
echo 'This ''string ''was ''made ''with multiple parameters.'chr(10);
echo 
'This ' 'string ' 'was ' 'made ' 'with concatenation.' "\n";

echo <<<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;

// 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
?>

注释

For a short discussion about the differences between print() and echo(), see this FAQTs Knowledge Base Article: » http://www.faqts.com/knowledge_base/view.phtml/aid/1/fid/40

Note: 由于这是一个语言结构而非函数,因此它无法被变量函数调用。

参见


Strings
PHP Manual