The full list of field-name characters that PHP converts to _ (underscore) is the following (not just dot):
chr(32) ( ) (space)
chr(46) (.) (dot)
chr(91) ([) (open square bracket)
chr(128) - chr(159) (various)
PHP irreversibly modifies field names containing these characters in an attempt to maintain compatibility with the deprecated register_globals feature.
來自 PHP 之外的變數
HTML 表單（GET 和 POST）
當一個表單體交給 PHP 腳本時，表單中的資訊會自動在腳本中可用。有很多方法訪問此資訊，例如：
Example #1 一個簡單的 HTML 表單
<form action="foo.php" method="POST">
Name: <input type="text" name="username"><br />
Email: <input type="text" name="email"><br />
<input type="submit" name="submit" value="Submit me!" />
</form>
根據特定的設置和個人的喜好，有很多種方法訪問 HTML 表單中的數據。例如：
Example #2 從一個簡單的 POST HTML 表單訪問數據
<?php
// 自 PHP 4.1.0 起可用
echo $_POST['username'];
echo $_REQUEST['username'];
import_request_variables('p', 'p_');
echo $p_username;
// 自 PHP 3 起可用。自 PHP 5.0.0 起，這些較長的預定義變數
// 可用 register_long_arrays 指令關閉。
echo $HTTP_POST_VARS['username'];
// 如果 PHP 指令 register_globals = on 時可用。不過自
// PHP 4.2.0 起默認值為 register_globals = off。
// 不提倡使用/依賴此種方法。
echo $username;
?>
使用 GET 表單也類似，只不過要用適當的 GET 預定義變數。GET 也適用於 QUERY_STRING（URL 中在「?」之後的資訊）。因此，舉例說，http://www.example.com/test.php?id=3 包含有可用 $_GET['id'] 訪問的 GET 數據。參見 $_REQUEST 和 import_request_variables()。
Note:
如上所示，在 PHP 4.2.0 之前 register_globals 的默認值是 on。在 PHP 3 中其值總是 on。PHP 社區鼓勵大家不要依賴此指令，建議在編碼時假定其為 off。
Note:
magic_quotes_gpc 配置指令影響到 Get，Post 和 Cookie 的值。如果打開，值 (It's "PHP!") 會自動轉換成 (It\'s \"PHP!\")。數據庫的插入就需要轉義。參見 addslashes()，stripslashes() 和 magic_quotes_sybase。
PHP 也懂得表單變數上下文中的數組（參見相關常見問題）。例如可以將相關的變數編成組，或者用此特性從多選輸入框中取得值。例如，將一個表單 POST 給自己並在提交時顯示數據：
Example #3 更複雜的表單變數
<?php
if (isset($_POST['action']) && $_POST['action'] == 'submitted') {
echo '<pre>';
print_r($_POST);
echo '<a href="'. $_SERVER['PHP_SELF'] .'">Please try again</a>';
echo '</pre>';
} else {
?>
<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
Name: <input type="text" name="personal[name]"><br />
Email: <input type="text" name="personal[email]"><br />
Beer: <br>
<select multiple name="beer[]">
<option value="warthog">Warthog</option>
<option value="guinness">Guinness</option>
<option value="stuttgarter">Stuttgarter Schwabenbr</option>
</select><br />
<input type="hidden" name="action" value="submitted" />
<input type="submit" name="submit" value="submit me!" />
</form>
<?php
}
?>
在 PHP 3 中，變數使用中的數組僅限於一維數組。在 PHP 4 中，沒有此種限制。
IMAGE SUBMIT 變數名
當提交表單時，可以用一幅圖像代替標準的提交按鈕，用類似這樣的標記：
<input type="image" src="image.gif" name="sub" />
當用戶點擊到圖像中的某處時，相應的表單會被傳送到服務器，並加上兩個變數 sub_x 和 sub_y。它們包含了用戶點擊圖像的坐標。有經驗的用戶可能會注意到被瀏覽器發送的實際變數名包含的是一個點而不是下劃線（即 sub.x 和 sub.y），但 PHP 自動將點轉換成了下劃線。
HTTP Cookies
PHP 透明地支持 » Netscape 規範定義中的 HTTP cookies。Cookies 是一種在遠端瀏覽器端存儲數據並能追蹤或識別再次訪問的用戶的機制。可以用 setcookie() 函式設定 cookies。Cookies 是 HTTP 資訊頭中的一部分，因此 SetCookie 函式必須在向瀏覽器發送任何輸出之前調用。對於 header() 函式也有同樣的限制。Cookie 數據會在相應的 cookie 數據數組中可用，例如 $_COOKIE，$HTTP_COOKIE_VARS 和 $_REQUEST。更多細節和例子見 setcookie() 手冊頁面。
如果要將多個值賦給一個 cookie 變數，必須將其賦成數組。例如：
<?php
setcookie("MyCookie[foo]", 'Testing 1', time()+3600);
setcookie("MyCookie[bar]", 'Testing 2', time()+3600);
?>
這將會建立兩個單獨的 cookie，儘管 MyCookie 在腳本中是一個單一的數組。如果想在僅僅一個 cookie 中設定多個值，考慮先在值上使用 serialize() 或 explode()。
注意在瀏覽器中一個 cookie 會替換掉上一個同名的 cookie，除非路徑或者域不同。因此對於購物車程序可以保留一個計數器並一起傳遞，例如：
Example #4 一個 setcookie() 的示例
<?php
if (isset($_COOKIE['count'])) {
$count = $_COOKIE['count'] + 1;
} else {
$count = 1;
}
setcookie('count', $count, time()+3600);
setcookie("Cart[$count]", $item, time()+3600);
?>
變數名中的點
通常，PHP 不會改變傳遞給腳本中的變數名。然而應該注意到點（句號）不是 PHP 變數名中的合法字元。至於原因，看看：
<?php
$varname.ext; /* 非法變數名 */
?>
出於此原因，要注意 PHP 將會自動將變數名中的點替換成下劃線。
確定變數類型
因為 PHP 會判斷變數類型並在需要時進行轉換（通常情況下），因此在某一時刻給定的變數是何種類型並不明顯。PHP 包括幾個函式可以判斷變數的類型，例如：gettype()，is_array()，is_float()，is_int()，is_object() 和 is_string()。參見類型一章。
add a note
User Contributed Notes 30 notes
Anonymous ¶
16 years ago
yasuo_ohgaki at hotmail dot com ¶
23 years ago
Important: Pay attention to the following security concerns when handling user submitted data :
http://www.php.net/manual/en/security.registerglobals.php
http://www.php.net/manual/en/security.variables.php
krydprz at iit dot edu ¶
18 years ago
This post is with regards to handling forms that have more than one submit button.
Suppose we have an HTML form with a submit button specified like this:
<input type="submit" value="Delete" name="action_button">
Normally the 'value' attribute of the HTML 'input' tag (in this case "Delete") that creates the submit button can be accessed in PHP after post like this:
<?php
$_POST['action_button'];
?>
We of course use the 'name' of the button as an index into the $_POST array.
This works fine, except when we want to pass more information with the click of this particular button.
Imagine a scenario where you're dealing with user management in some administrative interface. You are presented with a list of user names queried from a database and wish to add a "Delete" and "Modify" button next to each of the names in the list. Naturally the 'value' of our buttons in the HTML form that we want to display will be "Delete" and "Modify" since that's what we want to appear on the buttons' faceplates.
Both buttons (Modify and Delete) will be named "action_button" since that's what we want to index the $_POST array with. In other words, the 'name' of the buttons along cannot carry any uniquely identifying information if we want to process them systematically after submit. Since these buttons will exist for every user in the list, we need some further way to distinguish them, so that we know for which user one of the buttons has been pressed.
Using arrays is the way to go. Assuming that we know the unique numerical identifier of each user, such as their primary key from the database, and we DON'T wish to protect that number from the public, we can make the 'action_button' into an array and use the user's unique numerical identifier as a key in this array.
Our HTML code to display the buttons will become:
<input type="submit" value="Delete" name="action_button[0000000002]">
<input type="submit" value="Modify" name="action_button[0000000002]">
The 0000000002 is of course the unique numerical identifier for this particular user.
Then when we handle this form in PHP we need to do the following to extract both the 'value' of the button ("Delete" or "Modify") and the unique numerical identifier of the user we wish to affect (0000000002 in this case). The following will print either "Modify" or "Delete", as well as the unique number of the user:
<?php
$submitted_array = array_keys($_POST['action_button']);
echo ($_POST['action_button'][$submitted_array[0]] . " " . $submitted_array[0]);
?>
$submitted_array[0] carries the 0000000002.
When we index that into the $_POST['action_button'], like we did above, we will extract the string that was used as 'value' in the HTML code 'input' tag that created this button.
If we wish to protect the unique numerical identifier, we must use some other uniquely identifying attribute of each user. Possibly that attribute should be encrypted when output into the form for greater security.
Enjoy!
Anonymous ¶
21 years ago
"...the dot (period, full stop) is not a valid character in a PHP variable name."
That's not completely correct, consider this example:
$GLOBALS['foo.bar'] = 'baz';
echo ${'foo.bar'};
This will output baz as expected.
Anonymous ¶
10 years ago
From HTML 5.1 Draft:
http://www.w3.org/html/wg/drafts/html/master/forms.html#naming-form-controls:-the-name-attribute
The name content attribute gives the name of the form control, as used in form submission and in the form element's elements object. If the attribute is specified, its value must not be the empty string.
Any non-empty value for name is allowed.
So use the format like this <select multiple name="beer[]"> is still in the HTML 5 standard.
lennynyktyk at yahoo dot com ¶
19 years ago
When dealing with multiple select boxes and the name=some_name[] so that PHP will understand that is needs to interpet the input as an array an not as a single value. If you want to access this in Javascript you should assign an id attribute to the select box as well as the name attribute. Then proceed to use the id attribute in Javascript to reference the select box and the name attribute to reference the select box in PHP.
Example
<select multiple id="select_id" name="select_name[]">
....
</select>
<?PHP
echo $select_name[0];
?>
<script language="javascript">
document.forms[0].select_id.options[0].selected = true;
</script>
I hope you get the idea
tmk-php at infeline dot org ¶
19 years ago
To handle forms with or without [] you can do something like this:
<?php
function repairPost($data) {
// combine rawpost and $_POST ($data) to rebuild broken arrays in $_POST
$rawpost = "&".file_get_contents("php://input");
while(list($key,$value)= each($data)) {
$pos = preg_match_all("/&".$key."=([^&]*)/i",$rawpost, $regs, PREG_PATTERN_ORDER);
if((!is_array($value)) && ($pos > 1)) {
$qform[$key] = array();
for($i = 0; $i < $pos; $i++) {
$qform[$key][$i] = urldecode($regs[1][$i]);
}
} else {
$qform[$key] = $value;
}
}
return $qform;
}
// --- MAIN
$_POST = repairPost($_POST);
?>
The function will check every field in the $_POST with the raw post data and rebuild the arrays that got lost.
walf ¶
12 years ago
WARNING! replacement of spaces and dots does not occur in array keys.
E.g. If you have
<input name="a. b[x. y]" value="foo" />
var_dump($_POST);
gives
array(1) {
["a__b"]=>
array(1) {
["x. y"]=>
string(3) "foo"
}
}
a at b dot c dot de ¶
22 years ago
As far as whether or not "[]" in name attributes goes, The HTML4.01 specification only requires that it be a case-insensitive CDATA token, which can quite happily include "[]". Leading and trailing whitespace may be trimmed and shouldn't be used.
It is the id= attribute which is restricted, to a case-sensitive NAME token (not to be confused with a name= attribute).
anisgazis at gmail dot com ¶
5 years ago
Dots , spaces and [ in variable names are converted to underscores. For example
<input name="a.b" /> becomes $_REQUEST["a_b"].
<input name="a b" /> becomes $_REQUEST["a_b"].
<input name="a[b" /> becomes $_REQUEST["a_b"].
<input name="a]b" /> becomes $_REQUEST["a]b"].
<input name="a-b" /> becomes $_REQUEST["a-b"].
<input name="a/b" /> becomes $_REQUEST["a/b"].
<input name="a\b" /> becomes $_REQUEST["a\b"].
<input name="a,b" /> becomes $_REQUEST["a,b"].
fabian dot picone at gmail dot com ¶
5 years ago
"That will create two separate cookies although MyCookie will now be a single array in your script. If you want to set just one cookie with multiple values, consider using serialize() or explode() on the value first."
explode should be implode in this sentence.
vb at bertola dot eu dot org ¶
21 years ago
For what I understand, since PHP 4.3 it is possible to access the content of a POST request (or other methods as well) as an input stream named php://input, example:
readfile("php://input");
[to display it]
or
$fp = fopen("php://input", "r");
[to open it and then do whatever you want]
This is very useful to access the content of POST requests which actually have a content (and not just variable-value couples, which appear in $_POST).
This substitutes the old $HTTP_RAW_POST_DATA variable available in some of the previous 4.x versions. It is available for other upload methods different from POST too, but it is not available for POSTs with multipart/form-data content type, since the file upload handler has already taken care of the content in that case.
jlratwil at yahoo dot com ¶
19 years ago
To get multiple selected (with "multiple" ) lists in <select> tag, make sure that the "name" attribute is added to braces, like this:
<select multiple="multiple" name="users[]">
<option value="foo">Foo</option>
<option value="bar">Bar</option>
</select>
When submitted to PHP file (assume that you have a complete form) it will return an array of strings. Otherwise, it will just return the last element of the <select> tag you selected.
vierubino dot r3m0oFdisB1T at gmail dot com ¶
16 years ago
When you are using checkboxes to submit multiple choices, there is no need to use the complex method further down the page where you assign a unique name to each checkbox.
Instead, just name each checkbox as the same array, e.g.:
<input type="checkbox" name="items[]" value="foo" />
<input type="checkbox" name="items[]" value="bar" />
<input type="checkbox" name="items[]" value="baz" />
This way your $_POST["items"] variable will return as an array containing all and only the checkboxes that were clicked on.
kevinrlat nospam dot ccs dot neu dot edu ¶
20 years ago
if you use an array of checkboxes to submit info to a database or what have you, be careful of the case when no boxes are checked. for example:
<form method="post">
<input type="checkbox" name="checkstuff[]" value="0">
<input type="checkbox" name="checkstuff[]" value="1">
<input type="checkbox" name="checkstuff[]" value="2">
. . .
</form>
if these are submitted and none are checked, the $_POST['checkstuff'] variable will not contain an empty array, but a NULL value. this bothered me when trying to implode() the values of my checkboxes to insert into a database, i got a warning saying the 2nd argument was the wrong type.
hope this helps!
-kevin
t.montg AT gmail DOT com ¶
16 years ago
For anyone else having trouble figuring out how to access values in a SELECT element from a POST or GET form, you can't set the "id" attribute to the same thing as your "name" attribute. i.e. don't do this:
<?php
//Not so good
<select multiple="multiple" id="selectElem" name="selectElem[]">
<option value="ham">Ham</option>
<option value="cheese">Cheese</option>
<option value="hamcheese">Ham and Cheese</option>
</select>
?>
If you do the above, the variable $_POST['selectElem'] will not be set. Instead, either change the id or name attribute so that they are dissimilar. i.e. do this:
<?php
//So good (notice the new "id" value)
<select multiple="multiple" id="selectElemId" name="selectElem[]">
<option value="ham">Ham</option>
<option value="cheese">Cheese</option>
<option value="hamcheese">Ham and Cheese</option>
</select>
?>
Then you can access the value(s) of the SELECT element through the array $_POST['selectElem'][] or $_GET['selectElem'][]. It took me quite some time to figure out the problem.
POSTer ¶
14 years ago
Here's a simple function to give you an uncorrupted version of $_POST:
<?php
// Function to fix up PHP's messing up POST input containing dots, etc.
function getRealPOST() {
$pairs = explode("&", file_get_contents("php://input"));
$vars = array();
foreach ($pairs as $pair) {
$nv = explode("=", $pair);
$name = urldecode($nv[0]);
$value = urldecode($nv[1]);
$vars[$name] = $value;
}
return $vars;
}
?>
Murat TASARSU ¶
19 years ago
if you want your multiple select returned variable in comma seperated form you can use this. hope that helps. regards...
$myvariable
Array ( [0] => one [1] => two [2] => three )
turns into
one,two,three
<?php
$myvariable="";
$myseperator="";
foreach ( $_POST["myvariable"] as $v) {
if (!isset($nofirstcomma)) $nofirstcomma=0; else $myseperator=",";
$myvariable = $myvariable.$myseperator.$v;
}
echo $myvariable;
?>
carl_steinhilber at NOSPAMmentor dot com ¶
22 years ago
A group of identically-named checkbox form elements returning an array is a pretty standard feature of HTML forms. It would seem that, if the only way to get it to work is a non-HTML-standard-compliant workaround, it's a problem with PHP.
Since the array is passed in the header in a post, or the URL in a get, it's the PHP interpretation of those values that's failing.
ch1902uk at hotmail dot com ¶
18 years ago
Regarding image input buttons, above where it says:
"When the user clicks somewhere on the image, the accompanying form will be transmitted to the server with two *additional* variables, sub_x and sub_y. These contain the coordinates of the user click within the image."
This is the case with Firefox (and probably other standards browsers), however my experience with Internet Explorer is that when image inputs are clicked, they only submit the location of the click on the button and *not* the name of the input.
So if you have a form to move/delete entries like this
entry[] [delete_0] [up_0] [down_0]
entry[] [delete_1] [up_1] [down_1]
entry[] [delete_2] [up_2] [down_2]
Then submitting the form in firefox will give you post variables such as
<?php
$_POST['delete_2']; // "Delete" - button value
$_POST['delete_2_x']; // 23 - x coord
$_POST['delete_2_y']; // 3 - y coord
?>
In IE you only get
<?php
$_POST['delete_2_x']; // 23 - x coord
$_POST['delete_2_y']; // 3 - y coord
?>
So if you are checking for what button was clicked do something like this
<?php
for ($i = 0; $i < count($_POST['entry']); $i++)
{
if (isset($_POST['delete_' . $i . '_x']))
{
// do delete
}
}
?>
un shift at yahoo dot com ¶
21 years ago
This function takes a recurring form item from php://input and loads it into an array - useful for javascript/dom incompatibility with form_input_item[] names for checkboxes, multiple selects, etc. The fread maxes out at 100k on this one. I guess a more portable option would be pulling in ini_get('post_max_size') and converting it to an integer.
<?php
function multi_post_item($input_item_name) {
$array_output = array();
$in_handle = fopen("php://input", "r");
$raw_input_items = split("&", urldecode(fread($in_handle, 100000)));
foreach ($raw_input_items as $input_item) {
// split this item into name/value pair
$item = split("=", $input_item);
// form item name
$item_name = $item[0];
// form item value
$item_value = $item[1];
if ($item_name == $input_item_name) {
$array_output[] = $item_value;
}
}
return $array_output;
}
?>
hjncom at hjncom dot net ¶
21 years ago
I think '[' and ']' are valid characters for name attributes.
http://www.w3.org/TR/html401/interact/forms.html#h-17.4
-> InputType of 'name' attribute is 'CDATA'(not 'NAME' type)
http://www.w3.org/TR/html401/types.html#h-6.2
-> about CDATA('name' attribute is not 'NAME' type!)
...CDATA is a sequence of characters from the document character set and may include character entities...
http://www.w3.org/TR/html401/sgml/entities.html
--> about Character entity references in HTML 4
([ - [, ] - ])
Sadik_quake2003 at mail dot ru ¶
6 years ago
<form method="post">
<select name="selecter">
<option>one</option>
<option>two</option>
<option>three</option>
</select><br />
<input type="submit" value="send" />
</form>
<?=$_POST["selecter"];?>
If we change first option, that result will be: one (important: not null !)
darren at sullivan dot net ¶
20 years ago
This function is a simple solution for getting the array of selectes from a checkbox list or a dropdown list out of the Querry String. I took an example posted earlier and simplified it.
<?php
function multi_post_item($repeatedString) {
// Gets the specified array of multiple selects and/or
// checkboxes from the Query String
$ArrayOfItems = array();
$raw_input_items = split("&", $_SERVER["QUERY_STRING"]);
foreach ($raw_input_items as $input_item) {
$itemPair = split("=", $input_item);
if ($itemPair[0] == $repeatedString) {
$ArrayOfItems[] = $itemPair[1];
}
}
return $ArrayOfItems;
}
?>
Use the name of the field as the agrument. Example:
<?php
$Order = $_GET['Order'];
$Name = $_GET['Name'];
$States = multi_post_item('States');
$Products = multi_post_item('Products');
?>
Be sure to check for NULL if there are no selections or boxes checked.
tim at timpauly dot com ¶
18 years ago
This code module can be added to every form using require_once().
It will process any and all form data, prepending each variable with
a unique identifier (so you know which method was used to get the data).
My coding could be neater, but this sure makes processing forms much easier!
<?php
// -----------------------------------------------------------------
// Basic Data PHP module. This module captures all GET, POST
// and COOKIE data and processes it into variables.
// Coded April, 2005 by Timothy J. Pauly
// -----------------------------------------------------------------
//
// coo_ is prepended to each cookie variable
// get_ is prepended to each GET variable
// pos_ is prepended to each POST variable
// ses_ is prepended to each SESSION variable
// ser_ is prepended to each SERVER variable
session_start(); // initialize session data
$ArrayList = array("_POST", "_GET", "_SESSION", "_COOKIE", "_SERVER"); // create an array of the autoglobal arrays
// we want to process
foreach($ArrayList as $gblArray) // process each array in the array list
{
$prefx = strtolower(substr($gblArray,1,3))."_"; // derive the prepend string
// from the autoglobal type name
$tmpArray = $$gblArray;
$keys = array_keys($tmpArray); // extract the keys from the array being processed
foreach($keys as $key) // process each key
{
$arcnt = count($tmpArray[$key]);
if ($arcnt > 1) // Break down passed arrays and
// process each element seperately
{
$lcount = 0;
foreach ($tmpArray[$key] as $dval)
{
$prkey = $prefx.$key; // create a new key string
// with the prepend string added
$prdata['$prkey'] = $dval; // this step could be eliminated
${$prkey}[$lcount] = $prdata['$prkey']; //create new key and insert the data
$lcount++;
}
} else { // process passed single variables
$prkey = $prefx.$key; // create a new key string
// with the prepend string added
$prdata['$prkey'] = $tmpArray[$key]; // insert the data from
// the old array into the new one
$$prkey = $prdata['$prkey']; // create the newly named
// (prepended) key pair using variable variables :-)
}
}
}
// -------------------------------------------------------------
?>
arjini at mac dot com ¶
20 years ago
When dealing with form inputs named_like_this[5] and javascript, instead of trying to get PHP to do something fancy as mentioned below, just try this on the javascript side of things:
<form name="myForm">
<script>
my_fancy_input_name = 'array_of_things[1]';
/* now just refer to it like this in the dom tree
document[myForm][my_fancy_input_name].value
etc*/
</script>
<input type="text" name="array_of_things[1]" value="1"/>
</form>
No fancy PHP, in fact, you shouldn't need to change your PHP at all.
keli at kmdsz dot ro ¶
21 years ago
image type inputs apparently return their "value" argument from Mozilla, but not from IEXplorer... :(
example:
<input type="image" name="sb" value="first" src="first.jpg">
using a mozilla will give you
$sb="first" AND $sb_x, $sb_y ... whereas from IE there's just no $sb. :(
[this in short form, as I'm still using trackvars :) ]
jim at jamesdavis dot it ¶
20 years ago
How to pass a numerically indexed array.
This is the part inside the form. Notice that the name is not 'english[$r]' which you would normally write, but 'english[]'. PHP adds the index when it receives the post and it starts at 0.
<?php
for ($r=0; $r <= count($english)-1; $r++){
echo "<TEXTAREA NAME='english[]'>".$english[$r]."</TEXTAREA>";
}
?>
<?php
And this will get it out at the other end
function retrieve_english(){
for ($r=0; $r <= count($_POST['english'])-1; $r++){
echo $_POST['english'][$r]."<BR>";
}
}
?>
Keys are useful but so are numerical indices!
Cheers everyone
mattij at nitro fi no at no dot no ¶
19 years ago
If you try to refer or pass HTML-form data which has arrays with javascript remember that you should point to that array like this
<script type="text/javascript">
window.opener.document.forms[0]["to[where][we][point]"];
</script>
Sadik_quake2003 at mail dot ru ¶
6 years ago
<form method="post">
<select name="list">
<option>one</option>
<option>two</option>
<option>three</option>
</select><br />
<input type="submit" value="send" />
</form>
<?=$_POST["list"];?>
If we change first option, that result will be: one (important: not null !)
