crypt
A remedy to the problems caused by different management of returns between different platforms you can use the predefined constant PHP_EOF as the second parameter:
<?php
$foo = "foo";
$bar = "bar";
echo "Foo is $foo", PHP_EOL;
echo "Bar is $bar";
// is the same as using:
echo "Foo is $foo\n";
echo "Bar is $bar";
// but here only for UNIX-like platforms
?>
echo
(PHP 4, PHP 5)
echo — Извежда един или повече низове
Описание
void echo
( string $arg1
[, string $...
] )
Извежда всички параметри.
Всъщност echo() не е точно функция (а езикова конструкция), така че не е задължително използването на кръгли скоби при употребата й. echo() (за разлика от други езикови конструкции) не се държи като функция, така че, невинаги може да се използва в контекста на функция. Освен това, ако искате да предадете повече от един параметър към echo(), параметрите не трябва да бъдат в кръгли скоби.
echo() има и кратък синтаксис, при който веднага след отварящият таг се използва знак за равенството. Този кратък синтаксис работи само, ако конфигурационната настройка short_open_tag е включена.
I have <?=$foo?> foo.
Параметри
- arg1
-
Параметърът, който трябва да се изведе.
- ...
-
Връщани стойности
Няма връщана стойност.
Примери
Example #1 Примери за echo()
<?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\".";
// Може да използвате променливи в echo израза
$foo = "foobar";
$bar = "barbaz";
echo "foo is $foo"; // foo is foobar
// Също така може да ползвате масиви
$baz = array("value" => "foo");
echo "this is {$baz['value']} !"; // this is foo !
// При използването на единични кавички ще се изведе името на променливата, а не стойността й
echo 'foo is $foo'; // foo is $foo
// Ако не използвате други знаци, може просто да извеждате стойностите на променливи
echo $foo; // foobar
echo $foo,$bar; // foobarbarbaz
// Някои предпочитат да предават множество параметри за извеждане вместо да използват конкатенация.
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 $variable interpolation. Note
that the here document terminator must appear on a
line with just a semicolon. no extra whitespace!
END;
// Тъй като echo не се държи като функция, следният код е невалиден.
($some_var) ? echo 'true' : echo 'false';
// Все пак, следните примери ще работят:
($some_var) ? print 'true' : print 'false'; // print също е конструкция, но
// се държи като функция, така че,
// може да се използва в този контекст.
echo $some_var ? 'true': 'false'; // променен е израза
?>
Бележки
За кратка дискусия относно разликата между print() и echo(), вижте следната статия: » http://www.faqts.com/knowledge_base/view.phtml/aid/1/fid/40
Забележка: Тъй като това е езикова конструкция а не функция, тя не може да бъде извикана посредством променливи функции
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User Contributed Notes
echo
ximlabz at gmail dot com
05-Nov-2011 10:16
fire at dls dot net
29-Jul-2011 11:01
Pay attention to this part of the documentation:
echo() (unlike some other language constructs) does not behave like a function, so it cannot always be used in the context of a function
I was trying to make certain that I was detecting errors and was trying code like this:
@alwaysFails() or echo('Surprise! It failed again');
This error was generated:
[29-Jul-2011 12:56:19] PHP Parse error: syntax error, unexpected T_ECHO in /Applications/MAMP/test.php on line 12
Changing to die(), print() or a function I defined worked fine. Beware of this limitation of echo.
gbarros at yahoo-inc dot com
26-Jan-2010 02:10
just banged my head on this missing bits on the manual.
When using the <<< method, the array keys does not require any kind of quotes.
<?php
foreach ( $data as $i ){
echo <<< END
<tr>
<td>$i[date]</td>
<td>$i[name]</td>
</tr>
END;
}
?>
Let's hope you don't have any <?php echo $klingonships['th\'bl][ath']?> kind of array :)
Jakob Thomsen
23-Nov-2008 06:23
A way to color your echo output is to use shell_exec and the echo command (this only works on Linux/bash) in the following way:
<?php
echo shell_exec('echo "\e[0;31m Red color \e[0;32mGreen color \e[0m No color "');
?>
See http://wiki.archlinux.org/index.php/Color_Bash_Prompt for more colors and other options.
sandaimespaceman at gmail dot com
31-Aug-2008 11:25
Outputting \n won't generate a line break in the browser, <br /> is required for line break. Also,
<?php
echo "first line";
echo "second line";
?>
will like
first linesecond line
because you didn't insert spaces/line breaks.
the echo function can also be written like
<?php
echo ('text here')
?>
nikolaas dot mennega at links dot com dot au
31-Oct-2007 11:04
hemanman at gmail dot com, the problem is that func() doesn't actually return a value (string or otherwise), so the result of echoing func() is null.
With the comma version, each argument is evaluated and echoed in turn: first the literal string (simple), then func(). Evaluating a function call obviously calls the function (and in this case executes its own internal echo), and the result (null) is then echoed accordingly. So we end up with "outside func() within func()" as we would expect.
Thus:
<?php
echo "outside func ()\n", func ();
?>
effectively becomes:
<?php
echo "outside func ()\n";
//func ()
{
echo "within func ()\n";
}
echo '';
?>
The dot version is different: there's only one argument here, and it has to be fully evaluated before it can be echoed as requested. So we start at the beginning again: a literal string, no problem, then a concatenator, then a function call. Obviously the function call has to be evaluated before the result can be concatenated with the literal string, and THAT has to happen BEFORE we can complete the echo command. But evaluating func() produces its own call to echo, which promptly gets executed.
Thus:
<?php
echo "outside func ()\n" . func ();
?>
effectively becomes:
<?php
//func ()
{
echo "within func ()\n";
}
echo "outside func ()\n" . '';
?>
Jason Carlson - SiteSanity
16-May-2005 10:28
In response to Ryan's post with his echobig() function, using str_split wastes memory resources for what you are doing.
If all you want to do is echo smaller chunks of a large string, I found the following code to perform better and it will work in PHP versions 3+
<?php
function echobig($string, $bufferSize = 8192)
{
// suggest doing a test for Integer & positive bufferSize
for ($chars=strlen($string)-1,$start=0;$start <= $chars;$start += $bufferSize) {
echo substr($string,$start,$buffer_size);
}
}
?>
ryan at wonko dot com
27-Feb-2005 12:56
Due to the way TCP/IP packets are buffered, using echo to send large strings to the client may cause a severe performance hit. Sometimes it can add as much as an entire second to the processing time of the script. This even happens when output buffering is used.
If you need to echo a large string, break it into smaller chunks first and then echo each chunk. The following function will do the trick in PHP5:
<?php
function echobig($string, $bufferSize = 8192)
{
$splitString = str_split($string, $bufferSize);
foreach($splitString as $chunk)
echo $chunk;
}
?>
zombie)at(localm)dot(org)
25-Jan-2003 11:26
[Ed. Note: During normal execution, the buffer (where echo's arguments go) is not flushed (sent) after each write to the buffer. To do that you'd need to use the flush() function, and even that may not cause the data to be sent, depending on your web server.]
Echo is an i/o process and i/o processes are typically time consuming. For the longest time i have been outputting content by echoing as i get the data to output. Therefore i might have hundreds of echoes in my document. Recently, i have switched to concatenating all my string output together and then just doing one echo at the end. This organizes the code more, and i do believe cuts down on a bit of time. Likewise, i benchmark all my pages and echo seems to influence this as well. At the top of the page i get the micro time, and at the end i figure out how long the page took to process. With the old method of "echo as you go" the processing time seemed to be dependent on the user's net connection as well as the servers processing speed. This was probably due to how echo works and the sending of packets of info back and forth to the user. One an one script i was getting .0004 secs on a cable modem, and a friend of mine in on dialup was getting .2 secs. Finally, to test that echo is slow; I built strings of XML and XSLT and used the PHP sablotron functions to do a transformation and return a new string. I then echoed the string. Before the echo, the process time was around .025 seconds and .4 after the echo. So if you are big into getting the actual processing time of your scripts, don't include echoes since they seem to be user dependent. Note that this is just my experience and it could be a fluke.