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Last updated: Thu, 03 May 2007

echo

(PHP 4, PHP 5)

echo — 1つ以上の文字列を出力する

説明

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

この関数は、すべてのパラメータを出力します。

echo() は実際には関数ではありません (言語構造です) 。このため、使用する際に括弧は必要ありません。 (いくつかの他の言語構造と異なり) echo() は関数のように動作しません。そのため、常に関数のコンテキスト中で使用することはできません。加えて、複数のパラメータを指定して echo() をコールしたい場合、括弧の中にパラメータを記述するべきではありません。

例 2319. echo() の例


<?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\"."



// echo 命令の中で変数を使用することが可能です

$foo = "foobar";

$bar = "barbaz";



echo "foo is $foo"; // foo is foobar



// 配列を使用することもできます

$bar = array("value" => "foo");



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



// 値ではなく変数名を出力するシングルクオートを使用する。

echo 'foo is $foo'; // foo is $foo



// 他の文字を全く使用しない場合、echo 変数を使用可能です。

echo $foo;          // foobar

echo $foo,$bar;     // foobarbarbaz



// 複数のパラメータを結合してechoに渡そうとする人もいます

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;



// echo は関数のように動作しないので、以下のコードは正しくありません

($some_var) ? echo 'true' : echo 'false';



// しかし、次の例は動作します。

($some_var) ? print 'true' : print 'false'; // print も言語構造ですが、

                                            // 関数のように動作します。なので、

                                            // このコンテキスト中で使用できます

echo $some_var ? 'true': 'false'; // 命令を変更

?>

echo() には、開始タグの直後に等号を付ける短縮構文もあります。この短縮構文は、設定オプションshort_open_tagが有効な場合のみ使用可能です。


I have <?=$foo?> foo.

print()とecho()の違いに関する簡単な議論については、FAQTs Knowledge Base Article: » http://www.faqts.com/knowledge_base/view.phtml/aid/1/fid/40　を参照してください。

注意: これは、関数ではなく言語構造のため、可変関数を用いてコールすることはできません。

print(), printf(), flush() も参照ください。

add a note User Contributed Notes
echo

superwebdeveloper at gmail dot com
26-Apr-2007 03:39


I noticed something new with echo:



echo "You are viewing #" . $itemValue + 1 . " of a total of $announcementsCount announcements. <br />";



causes "You are viewing #"  to not appear in the output.



putting parenthesis around the math resolves the issue.



echo "You are viewing #" . ($itemValue + 1) . " of a total of $announcementsCount announcements. <br />";



this may not be so much a bug as something that happens for a darn good reason. Im just not sure of the reason.

Jim Walker
14-Jan-2007 04:24


Putting the constant value __LINE__ in debugging messages can save time locating the message line in your source. You can use the same message text in more than one location and the message will be unique. For example,



     echo __LINE__.' My Array: '.$k.' = '.$v.'<br>';

Meercat9
14-Dec-2006 01:12


<table align=center>

<?

//Using Backslashes Does not Make the Quotation Marks Not Execute, Only Separates them From the Others.

 echo "<tr align=center bgcolor=#1A1A1A onMouseOver=\"this.bgColor='#33333';\" onMouseOut=\"this.bgColor='#1A1A1A';\">"

?>

</table>



Which Can Work Similar if You Want to Store Some Java Incorporated HTML in a String Variable.



<?

  $table = "<table align=\"center\">

  $td = "<tr align=center bgcolor=#1A1A1A onMouseOver=\"this.bgColor='#33333';\" onMouseOut=\"this.bgColor='#1A1A1A';\">";

  $td = "<td align=\"center\">";



echo "<$table \n $tr \n $td \n Hello </td>\n</tr>\n</table>"

?>

rwruck
28-Jan-2006 06:15


It should be mentioned here that the script will be aborted if you output something in response to a HTTP HEAD request.

In the following example, the second line will NOT be written to the file. Any registered shutdown function will be called, though:



<?php

$hf = fopen('head.log', 'ab');

fwrite($hf, "before output\n");

echo "Test";

fwrite($hf, "after output\n");

fclose($hf);

?>



This is normal behaviour; see the description of $_SERVER.

lorenpr at gmail dot com
15-Sep-2005 01:12


I hope this ternary thing isn't overkill. Last thing - I would just like to make you aware of the side effect when you do this statement, 

 

echo $some_var ? print 'true': print 'false';



The result would be either 'true1' or 'false1', depending on whether $some_var is true or false respectively. This happens because of what I mentioned earlier. Figure it out.

lorenpr at gmail dot com
15-Sep-2005 12:58


linus is correct.

The ternary relationship is evaluated first, then echo prints the result.



Also, keep in mind

(condition? a : b) 

reads 

if(condition) return a; else return b;



So what makes 

A. echo ($somevar) ? 'true' : 'false';



different from



B. ($somevar) ? echo 'true' : echo 'false';



is the ternary relationship in A reads

if (condition) return 'true'; else return 'false';



while in B it reads

if(condition) return (echo 'true'); else return (echo 'false');



- an invalid statement, since echo evaluates to void.

linus.martensson a gmail
25-Aug-2005 06:03


Simple. it reads like echo (($somevar)?'true';'false'); and outputs the result, unless I'm mistaken.

shannonmoeller at gmail dot com
10-Aug-2005 08:31


In reply to lorenpr at gmail dot com:



If what you say is true, why does this work?



<?php

echo ($somevar) ? 'true' : 'false'; //works

?>

lorenpr at gmail dot com
29-Jul-2005 02:17


I just want to point out something to beginners. The documentation is misleading where it says:



// Because echo is not a function, following code is invalid.

($some_var) ? echo 'true' : echo 'false';



The code is invalid, but not because 'echo' is a language construct, but rather because 'echo' does not return a value. 

So don't be mislead: the syntax used above is certainly not limited to functions.



You must keep in mind that the job of the ternary syntax used is not actually to display anything, but to test a boolean relationship. The 'print' statement would work because it always returns a 1, which in php, is interpreted to a boolean  'true'. Things that return 'void' cannot be expected to evaluate to a 'true' or 'false', and that is why using 'echo' in this particular case is invalid.

Jason Carlson - SiteSanity
17-May-2005 02:28


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);

  }

}

?>

renrutal at gmail dot com
29-Mar-2005 08:34


Note that:



<?php

echo "2 + 2 = " . 2+2; // This will print 4

echo "2 + 2 = " , 2+2; // This will print 2+2 = 4

?>



The commas will parse the result of the expressions correctly.

ryan at wonko dot com
27-Feb-2005 05:56


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;

}

?>

Truffy
15-Jan-2005 06:02


You can use braces around variables as well as array items. This is useful to help recognition of your variables in your code, but most useful where the variable iteslf cannot be separated with spaces from the preceding/following code, for exmple in a file path:



If a path is assigned the variable $path, then this code will not work:



echo "$pathindex.php";



whereas this will



echo "{$path}index.php";

zombie)at(localm)dot(org)
26-Jan-2003 04:26


[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.

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explode

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crypt

Last updated: Thu, 03 May 2007