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explode> <crypt
Last updated: Fri, 13 Nov 2009

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echo

(PHP 4, PHP 5)

echoExibe uma ou mais strings

Descrição

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

Exibe todos os parâmetros.

echo() não é uma função atualmente (construtor da linguagem) então não é obrigatório usar parênteses. echo() (diferente de outro construtor da linguagem) não se comporta como uma função, então ele nem sempre é usado no contexto de uma função. Sendo assim, se você quer passar mais de um parâmetro para echo(), os parâmetros não precisam estar entre parênteses.

echo() também tem um sintaxe curta, onde você pode imediatamente abrir a tag com o sinal de igual. Esta sintaxe curta funciona habilitando a definição da configuração short_open_tag.

I have <?=$foo?> foo.

Parâmetros

arg1

O parâmetro a exibir.

...

Valor Retornado

Não há valor retornado.

Exemplos

Exemplo #1 echo() exemplos

<?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
?>

Notas

Para uma pequena discussão sobre a diferença entre print() e echo(), veja este FAQTs Knowledge Base Article: » http://www.faqts.com/knowledge_base/view.phtml/aid/1/fid/40

Nota: Este é um construtor de linguagem e não uma função, por isso não é possível chamá-lo através de funções variáveis

Veja Também



explode> <crypt
Last updated: Fri, 13 Nov 2009
 
add a note add a note User Contributed Notes
echo
Jakob Thomsen
23-Nov-2008 02:23
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
01-Sep-2008 06:25
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
01-Nov-2007 07:04
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:

<?
echo "outside func ()\n", func ();
?>

effectively becomes:

<?
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:

<?
echo "outside func ()\n" . func ();
?>

effectively becomes:

<?
//func ()
{
echo "within func ()\n";
}
echo "outside func ()\n" . '';
?>
Jason Carlson - SiteSanity
16-May-2005 05:28
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 08:56
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 07:26
[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.

explode> <crypt
Last updated: Fri, 13 Nov 2009
 
 
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