Joining string, variable, and array index all together to a variable - php

I'm trying to do something out of my league, but I don't see how else I can achieve it.
I have two array variables.
<?php
$mobile_eu = array("alb", "bul");
$m_alb = array(array("Albanian"), array("test#test.com"),
array("test2#test.com", "test3#test.com");
?>
What I'm trying to do is, get alb from $mobile_eu, prepend a string to the value, and then access $m_alb from it with [0][0] index. Something like...
function createLink($category) {
foreach ($category as $short) {
$langcode = "\$m_" . $short . [0][0];
}
}
and yes, it doesn't work. When I dumped it, all it shows is
string 'alb0' (length=4)
What I hope to achieve here is to get
string 'Albanian' (length=8)
Is there any way to get this?
Any help would be great.
Thanks.

<?php
$mobile_eu = array("alb", "bul");
$m_alb = array(array("Albanian"), array("test#test.com"),
array("test2#test.com", "test3#test.com"));
echo ${'m_'.$mobile_eu[0]}[0][0];
prints Albania.
see also: http://docs.php.net/language.variables.variable
But I think you should structure your data in another way, so you don't need something like this. E.g. instead of having a variable $m_alb and another $m_bul you could have an array where 'alb' and 'bul' are keys/elements:
<?php
createLinks( array('alb','bul') );
function createLinks($regions) {
static $data = array ( /* using static only as an example for "some data source" */
'alb' => array(
array("Albanian"), /* it would certainly be nice if you could give */
array("test#test.com"), /* those elements key-names with some meaning */
array("test2#test.com", "test3#test.com")
),
'bul' => array(
array("Bulgaria"),
array("test5#test.com"),
array("test6#test.com", "test7#test.com")
),
);
foreach( $regions as $r ) {
echo $data[$r][0][0], "<br />\r\n";
}
}

Might be this will helps you.
Solution : I have made some modifications in your createlink function Kindly check those as below:
function createLink($category) {
foreach ($category as $short) {
global $m_alb;
$arrayName = "m_" . $short;
$newArray = $$arrayName;
var_dump($newArray[0][0]);
}
}
I have made $m_alb array as the global because the with out this we will get an Notice: Undefined variable: m_alb. As the $m_alb array is not in the scope of createlink function. Now you can call your createlink function and check the result.
Hope this will works for you.

Related

Is it possible to pass a function as another function parameter? [duplicate]

I need to pass a function as a parameter to another function and then call the passed function from within the function...This is probably easier for me to explain in code..I basically want to do something like this:
function ($functionToBeCalled)
{
call($functionToBeCalled,additional_params);
}
Is there a way to do that.. I am using PHP 4.3.9
Thanks!
I think you are looking for call_user_func.
An example from the PHP Manual:
<?php
function barber($type) {
echo "You wanted a $type haircut, no problem";
}
call_user_func('barber', "mushroom");
call_user_func('barber', "shave");
?>
function foo($function) {
$function(" World");
}
function bar($params) {
echo "Hello".$params;
}
$variable = 'bar';
foo($variable);
Additionally, you can do it this way. See variable functions.
In php this is very simple.
<?php
function here() {
print 'here';
}
function dynamo($name) {
$name();
}
//Will work
dynamo('here');
//Will fail
dynamo('not_here');
I know the original question asked about PHP 4.3, but now it's a few years later and I just wanted to advocate for my preferred way to do this in PHP 5.3 or higher.
PHP 5.3+ now includes support for anonymous functions (closures), so you can use some standard functional programming techniques, as in languages like JavaScript and Ruby (with a few caveats). Rewriting the call_user_func example above in "closure style" would look like this, which I find more elegant:
$barber = function($type) {
echo "You wanted a $type haircut, no problem\n";
};
$barber('mushroom');
$barber('shave');
Obviously, this doesn't buy you much in this example - the power and flexibility comes when you pass these anonymous functions to other functions (as in the original question). So you can do something like:
$barber_cost = function($quantity) {
return $quantity * 15;
};
$candy_shop_cost = function($quantity) {
return $quantity * 4.50; // It's Moonstruck chocolate, ok?
};
function get_cost($cost_fn, $quantity) {
return $cost_fn($quantity);
}
echo '3 haircuts cost $' . get_cost($barber_cost, 3) . "\n";
echo '6 candies cost $' . get_cost($candy_shop_cost, 6) . "\n";
This could be done with call_user_func, of course, but I find this syntax much clearer, especially once namespaces and member variables get involved.
One caveat: I'll be the first to admit I don't know exactly what's going on here, but you can't always call a closure contained in a member or static variable, and possibly in some other cases. But reassigning it to a local variable will allow it to be invoked. So, for example, this will give you an error:
$some_value = \SomeNamespace\SomeClass::$closure($arg1, $arg2);
But this simple workaround fixes the issue:
$the_closure = \SomeNamespace\SomeClass::$closure;
$some_value = $the_closure($arg1, $arg2);
You could also use call_user_func_array(). It allows you to pass an array of parameters as the second parameter so you don't have to know exactly how many variables you're passing.
If you need pass function with parameter as parameter, you can try this:
function foo ($param1){
return $param1;
}
function bar ($foo_function, $foo_param){
echo $foo_function($foo_param);
}
//call function bar
bar('foo', 'Hi there'); //this will print: 'Hi there'
phpfiddle example
Hope it'll be helpful...
If you want to do this inside a PHP Class, take a look at this code:
// Create a sample class
class Sample
{
// Our class displays 2 lists, one for images and one for paragraphs
function __construct( $args ) {
$images = $args['images'];
$items = $args['items'];
?>
<div>
<?php
// Display a list of images
$this->loop( $images, 'image' );
// notice how we pass the name of the function as a string
// Display a list of paragraphs
$this->loop( $items, 'content' );
// notice how we pass the name of the function as a string
?>
</div>
<?php
}
// Reuse the loop
function loop( $items, $type ) {
// if there are items
if ( $items ) {
// iterate through each one
foreach ( $items as $item ) {
// pass the current item to the function
$this->$type( $item );
// becomes $this->image
// becomes $this->content
}
}
}
// Display a single image
function image( $item ) {
?>
<img src="<?php echo $item['url']; ?>">
<?php
}
// Display a single paragraph
function content( $item ) {
?>
<p><?php echo $item; ?></p>
<?php
}
}
// Create 2 sample arrays
$images = array( 'image-1.jpg', 'image-2.jpg', 'image-3.jpg' );
$items = array( 'sample one', 'sample two', 'sample three' );
// Create a sample object to pass my arrays to Sample
$elements = { 'images' => $images, 'items' => $items }
// Create an Instance of Sample and pass the $elements as arguments
new Sample( $elements );

How do I make a function reference in PHP?

I'm trying to make an associative array with values that are references to functions. What is the proper way to do this? This code works, but gives me a warning.
Code
<?php
$mergeCodes = array(
'rev:(\d+)' => reverse_me,
);
$test = "This is a [[rev:1234]] test";
echo "BEFORE: $test\n";
foreach ($mergeCodes as $code => $callback) {
$code = '\[\[' . $code . '\]\]';
$test = preg_replace_callback( "/$code/", $callback, $test );
}
echo "AFTER: $test\n";
function reverse_me($input) {
return strrev($input[1]);
}
?>
Output
PHP Notice: Use of undefined constant reverse_me - assumed 'reverse_me' in /tmp/test2.php on line 4
BEFORE: This is a [[rev:1234]] test
AFTER: This is a 4321 test
As far as I know, PHP does not have such concept. You're probably confused by JavaScript.
It seems that your final purpose is to make a call to preg_replace_callback(). As the name suggests you have to feed it with a callback and that's something pretty simple. All you need is a regular variable that contains one of these:
A string with a variable name: 'foo'
An array with a class name and a method name: array('Foo', 'doBar')
An array with a class instance and a method name: array($myFoo, 'doBar')
Find further reference at https://www.php.net/manual/en/language.types.callable.php
In PHP 5.3, you can store anonymous functions (closures) in variables:
$reverse_me = function($input) {
return strrev($input[1]);
}
$mergeCodes = array(
'rev:(\d+)' => $reverse_me
);
Or you could even do this:
$mergeCodes = array(
'rev:(\d+)' => function($input) {
return strrev($input[1]);
}
);
See http://php.net/functions.anonymous for more info.
I fixed it by making the value the string 'reverse_me'. I guess $callback being a string was not very intuitive to me.

How to pass series of variables in function as array or regardless of their order?

I am sorry, that sounds like a noob question. I am trying to do this, maybe my question is not clear.
I want to be able to pass something like this:
make_thumbnail( array( 'width' => 60, 'height' => 40', 'title' => 'my image' ) );
Now the above line calls the function which already produces the thumbnails I have that no problem, but I want flexibility here. I mean my function has variables ordered like this:
function make_thumbnail($title,$width,$height) {
the code..
echo ...
}
Now you get what I want to do? I want to be able to pass the variables in any order.. they do not have to come in same order title, width, height.. i want to be able to specify the order when I call the function in template as I put in very first line.
I tried to make my question as clear as I can, but really could not find anything about it.
This sort of thing?
function make_thumbnail($myarray) {
$sometitle = $myarray["title"]
$somewidth = $myarray["width"]
$someheight = $myarray["height"]
}
Why not have the array as the function argument? e.g.
function make_thumbnail($argsArray) {
echo $argsArray['width'];
}
You can create variables within your function for each parameter
function make_thumbnail($argsArray) {
$width = $argsArray['width'];
$height = $argsArray['height'];
$title = $argsArray['title'];
// ...plug the rest of your original function here
}
Then your function will behave exactly the same, except you can pass in an array.
What you're asking for is a description of the Reflection syntax of PHP:
function callWithNamedParams( $funcName, array $args = null )
{
if( is_null( $args ) ) return $funcName();
$f = new ReflectionFunction($funcName);
$input = array();
foreach( $f->getParameters() as $param )
{
array_push( $input, #$args[ $param->getName() ] );
}
return call_user_func_array( $funcName, $input );
}
Use:
function myFunc( $foo, $bar )
{
echo "foo = $foo; Bar = $bar";
}
callWithNamedParams( "myFunc", array( "bar"=>1, "foo"=>2 ) );
You should get foo = 2; Bar = 1 as an output.
you need to define your logic to take any parameter as the one you want it to be. Array is the best thing you can use. But changing the parameters changes the signatures.
you are kinda implementing polymorphism but in a wrong way..

How to determine user defined function parameters names before calling it?

In PHP, I have created a user defined function. Example:
<?php
function test($one, $two) {
// do things
}
?>
I would like to find the names of the function parameters. How would I go about doing this?
This is an example of what I would like:
<?php
function test($one, $two) {
// do things
}
$params = magic_parameter_finding_function('test');
print_r($params);
?>
This would output:
Array
(
[0] => one
[1] => two
)
Also this is very important that I am able to get the user defined function parameter names outside the scope of the function. Thanks in advance!
You can do this using reflection...
$reflector = new ReflectionFunction('test');
$params = array();
foreach ($reflector->getParameters() as $param) {
$params[] = $param->name;
}
print_r($params);
you can use count_parameter a php built in function

How to get a variable name as a string in PHP?

Say i have this PHP code:
$FooBar = "a string";
i then need a function like this:
print_var_name($FooBar);
which prints:
FooBar
Any Ideas how to achieve this? Is this even possible in PHP?
I couldn't think of a way to do this efficiently either but I came up with this. It works, for the limited uses below.
shrug
<?php
function varName( $v ) {
$trace = debug_backtrace();
$vLine = file( __FILE__ );
$fLine = $vLine[ $trace[0]['line'] - 1 ];
preg_match( "#\\$(\w+)#", $fLine, $match );
print_r( $match );
}
$foo = "knight";
$bar = array( 1, 2, 3 );
$baz = 12345;
varName( $foo );
varName( $bar );
varName( $baz );
?>
// Returns
Array
(
[0] => $foo
[1] => foo
)
Array
(
[0] => $bar
[1] => bar
)
Array
(
[0] => $baz
[1] => baz
)
It works based on the line that called the function, where it finds the argument you passed in. I suppose it could be expanded to work with multiple arguments but, like others have said, if you could explain the situation better, another solution would probably work better.
You could use get_defined_vars() to find the name of a variable that has the same value as the one you're trying to find the name of. Obviously this will not always work, since different variables often have the same values, but it's the only way I can think of to do this.
Edit: get_defined_vars() doesn't seem to be working correctly, it returns 'var' because $var is used in the function itself. $GLOBALS seems to work so I've changed it to that.
function print_var_name($var) {
foreach($GLOBALS as $var_name => $value) {
if ($value === $var) {
return $var_name;
}
}
return false;
}
Edit: to be clear, there is no good way to do this in PHP, which is probably because you shouldn't have to do it. There are probably better ways of doing what you're trying to do.
You might consider changing your approach and using a variable variable name?
$var_name = "FooBar";
$$var_name = "a string";
then you could just
print($var_name);
to get
FooBar
Here's the link to the PHP manual on Variable variables
No-one seems to have mentioned the fundamental reasons why this is a) hard and b) unwise:
A "variable" is just a symbol pointing at something else. In PHP, it internally points to something called a "zval", which can actually be used for multiple variables simultaneously, either because they have the same value (PHP implements something called "copy-on-write" so that $foo = $bar doesn't need to allocate extra memory straight away) or because they have been assigned (or passed to a function) by reference (e.g. $foo =& $bar). So a zval has no name.
When you pass a parameter to a function you are creating a new variable (even if it's a reference). You could pass something anonymous, like "hello", but once inside your function, it's whatever variable you name it as. This is fairly fundamental to code separation: if a function relied on what a variable used to be called, it would be more like a goto than a properly separate function.
Global variables are generally considered a bad idea. A lot of the examples here assume that the variable you want to "reflect" can be found in $GLOBALS, but this will only be true if you've structured your code badly and variables aren't scoped to some function or object.
Variable names are there to help programmers read their code. Renaming variables to better suit their purpose is a very common refactoring practice, and the whole point is that it doesn't make any difference.
Now, I understand the desire for this for debugging (although some of the proposed usages go far beyond that), but as a generalised solution it's not actually as helpful as you might think: if your debug function says your variable is called "$file", that could still be any one of dozens of "$file" variables in your code, or a variable which you have called "$filename" but are passing to a function whose parameter is called "$file".
A far more useful piece of information is where in your code the debug function was called from. Since you can quickly find this in your editor, you can see which variable you were outputting for yourself, and can even pass whole expressions into it in one go (e.g. debug('$foo + $bar = ' . ($foo + $bar))).
For that, you can use this snippet at the top of your debug function:
$backtrace = debug_backtrace();
echo '# Debug function called from ' . $backtrace[0]['file'] . ' at line ' . $backtrace[0]['line'];
This is exactly what you want - its a ready to use "copy and drop in" function that echo the name of a given var:
function print_var_name(){
// read backtrace
$bt = debug_backtrace();
// read file
$file = file($bt[0]['file']);
// select exact print_var_name($varname) line
$src = $file[$bt[0]['line']-1];
// search pattern
$pat = '#(.*)'.__FUNCTION__.' *?\( *?(.*) *?\)(.*)#i';
// extract $varname from match no 2
$var = preg_replace($pat, '$2', $src);
// print to browser
echo '<pre>' . trim($var) . ' = ' . print_r(current(func_get_args()), true) . '</pre>';
}
USAGE: print_var_name($FooBar)
PRINT: FooBar
HINT
Now you can rename the function and it will still work and also use the function several times in one line! Thanks to #Cliffordlife
And I add a nicer output! Thanks to #Blue-Water
Lucas on PHP.net provided a reliable way to check if a variable exists. In his example, he iterates through a copy of the global variable array (or a scoped array) of variables, changes the value to a randomly generated value, and checks for the generated value in the copied array.
function variable_name( &$var, $scope=false, $prefix='UNIQUE', $suffix='VARIABLE' ){
if($scope) {
$vals = $scope;
} else {
$vals = $GLOBALS;
}
$old = $var;
$var = $new = $prefix.rand().$suffix;
$vname = FALSE;
foreach($vals as $key => $val) {
if($val === $new) $vname = $key;
}
$var = $old;
return $vname;
}
Then try:
$a = 'asdf';
$b = 'asdf';
$c = FALSE;
$d = FALSE;
echo variable_name($a); // a
echo variable_name($b); // b
echo variable_name($c); // c
echo variable_name($d); // d
Be sure to check his post on PHP.net: http://php.net/manual/en/language.variables.php
I made an inspection function for debugging reasons. It's like print_r() on steroids, much like Krumo but a little more effective on objects. I wanted to add the var name detection and came out with this, inspired by Nick Presta's post on this page. It detects any expression passed as an argument, not only variable names.
This is only the wrapper function that detects the passed expression.
Works on most of the cases.
It will not work if you call the function more than once in the same line of code.
This works fine:
die(inspect($this->getUser()->hasCredential("delete")));
inspect() is the function that will detect the passed expression.
We get: $this->getUser()->hasCredential("delete")
function inspect($label, $value = "__undefin_e_d__")
{
if($value == "__undefin_e_d__") {
/* The first argument is not the label but the
variable to inspect itself, so we need a label.
Let's try to find out it's name by peeking at
the source code.
*/
/* The reason for using an exotic string like
"__undefin_e_d__" instead of NULL here is that
inspected variables can also be NULL and I want
to inspect them anyway.
*/
$value = $label;
$bt = debug_backtrace();
$src = file($bt[0]["file"]);
$line = $src[ $bt[0]['line'] - 1 ];
// let's match the function call and the last closing bracket
preg_match( "#inspect\((.+)\)#", $line, $match );
/* let's count brackets to see how many of them actually belongs
to the var name
Eg: die(inspect($this->getUser()->hasCredential("delete")));
We want: $this->getUser()->hasCredential("delete")
*/
$max = strlen($match[1]);
$varname = "";
$c = 0;
for($i = 0; $i < $max; $i++){
if( $match[1]{$i} == "(" ) $c++;
elseif( $match[1]{$i} == ")" ) $c--;
if($c < 0) break;
$varname .= $match[1]{$i};
}
$label = $varname;
}
// $label now holds the name of the passed variable ($ included)
// Eg: inspect($hello)
// => $label = "$hello"
// or the whole expression evaluated
// Eg: inspect($this->getUser()->hasCredential("delete"))
// => $label = "$this->getUser()->hasCredential(\"delete\")"
// now the actual function call to the inspector method,
// passing the var name as the label:
// return dInspect::dump($label, $val);
// UPDATE: I commented this line because people got confused about
// the dInspect class, wich has nothing to do with the issue here.
echo("The label is: ".$label);
echo("The value is: ".$value);
}
Here's an example of the inspector function (and my dInspect class) in action:
http://inspect.ip1.cc
Texts are in spanish in that page, but code is concise and really easy to understand.
From php.net
#Alexandre - short solution
<?php
function vname(&$var, $scope=0)
{
$old = $var;
if (($key = array_search($var = 'unique'.rand().'value', !$scope ? $GLOBALS : $scope)) && $var = $old) return $key;
}
?>
#Lucas - usage
<?php
//1. Use of a variable contained in the global scope (default):
$my_global_variable = "My global string.";
echo vname($my_global_variable); // Outputs: my_global_variable
//2. Use of a local variable:
function my_local_func()
{
$my_local_variable = "My local string.";
return vname($my_local_variable, get_defined_vars());
}
echo my_local_func(); // Outputs: my_local_variable
//3. Use of an object property:
class myclass
{
public function __constructor()
{
$this->my_object_property = "My object property string.";
}
}
$obj = new myclass;
echo vname($obj->my_object_property, $obj); // Outputs: my_object_property
?>
Many replies question the usefulness of this. However, getting a reference for a variable can be very useful. Especially in cases with objects and $this. My solution works with objects, and as property defined objects as well:
function getReference(&$var)
{
if(is_object($var))
$var->___uniqid = uniqid();
else
$var = serialize($var);
$name = getReference_traverse($var,$GLOBALS);
if(is_object($var))
unset($var->___uniqid);
else
$var = unserialize($var);
return "\${$name}";
}
function getReference_traverse(&$var,$arr)
{
if($name = array_search($var,$arr,true))
return "{$name}";
foreach($arr as $key=>$value)
if(is_object($value))
if($name = getReference_traverse($var,get_object_vars($value)))
return "{$key}->{$name}";
}
Example for the above:
class A
{
public function whatIs()
{
echo getReference($this);
}
}
$B = 12;
$C = 12;
$D = new A;
echo getReference($B)."<br/>"; //$B
echo getReference($C)."<br/>"; //$C
$D->whatIs(); //$D
Adapted from answers above for many variables, with good performance, just one $GLOBALS scan for many
function compact_assoc(&$v1='__undefined__', &$v2='__undefined__',&$v3='__undefined__',&$v4='__undefined__',&$v5='__undefined__',&$v6='__undefined__',&$v7='__undefined__',&$v8='__undefined__',&$v9='__undefined__',&$v10='__undefined__',&$v11='__undefined__',&$v12='__undefined__',&$v13='__undefined__',&$v14='__undefined__',&$v15='__undefined__',&$v16='__undefined__',&$v17='__undefined__',&$v18='__undefined__',&$v19='__undefined__'
) {
$defined_vars=get_defined_vars();
$result=Array();
$reverse_key=Array();
$original_value=Array();
foreach( $defined_vars as $source_key => $source_value){
if($source_value==='__undefined__') break;
$original_value[$source_key]=$$source_key;
$new_test_value="PREFIX".rand()."SUFIX";
$reverse_key[$new_test_value]=$source_key;
$$source_key=$new_test_value;
}
foreach($GLOBALS as $key => &$value){
if( is_string($value) && isset($reverse_key[$value]) ) {
$result[$key]=&$value;
}
}
foreach( $original_value as $source_key => $original_value){
$$source_key=$original_value;
}
return $result;
}
$a = 'A';
$b = 'B';
$c = '999';
$myArray=Array ('id'=>'id123','name'=>'Foo');
print_r(compact_assoc($a,$b,$c,$myArray) );
//print
Array
(
[a] => A
[b] => B
[c] => 999
[myArray] => Array
(
[id] => id123
[name] => Foo
)
)
If the variable is interchangable, you must have logic somewhere that's determining which variable gets used. All you need to do is put the variable name in $variable within that logic while you're doing everything else.
I think we're all having a hard time understanding what you're needing this for. Sample code or an explanation of what you're actually trying to do might help, but I suspect you're way, way overthinking this.
I actually have a valid use case for this.
I have a function cacheVariable($var) (ok, I have a function cache($key, $value), but I'd like to have a function as mentioned).
The purpose is to do:
$colour = 'blue';
cacheVariable($colour);
...
// another session
...
$myColour = getCachedVariable('colour');
I have tried with
function cacheVariable($variable) {
$key = ${$variable}; // This doesn't help! It only gives 'variable'.
// do some caching using suitable backend such as apc, memcache or ramdisk
}
I have also tried with
function varName(&$var) {
$definedVariables = get_defined_vars();
$copyOfDefinedVariables = array();
foreach ($definedVariables as $variable=>$value) {
$copyOfDefinedVariables[$variable] = $value;
}
$oldVar = $var;
$var = !$var;
$difference = array_diff_assoc($definedVariables, $copyOfDefinedVariables);
$var = $oldVar;
return key(array_slice($difference, 0, 1, true));
}
But this fails as well... :(
Sure, I could continue to do cache('colour', $colour), but I'm lazy, you know... ;)
So, what I want is a function that gets the ORIGINAL name of a variable, as it was passed to a function. Inside the function there is no way I'm able to know that, as it seems. Passing get_defined_vars() by reference in the second example above helped me (Thanks to Jean-Jacques Guegan for that idea) somewhat. The latter function started working, but it still only kept returning the local variable ('variable', not 'colour').
I haven't tried yet to use get_func_args() and get_func_arg(), ${}-constructs and key() combined, but I presume it will fail as well.
I have this:
debug_echo(array('$query'=>$query, '$nrUsers'=>$nrUsers, '$hdr'=>$hdr));
I would prefer this:
debug_echo($query, $nrUsers, $hdr);
The existing function displays a yellow box with a red outline and shows each variable by name and value. The array solution works but is a little convoluted to type when it is needed.
That's my use case and yes, it does have to do with debugging. I agree with those who question its use otherwise.
Here's my solution based on Jeremy Ruten
class DebugHelper {
function printVarNames($systemDefinedVars, $varNames) {
foreach ($systemDefinedVars as $var=>$value) {
if (in_array($var, $varNames )) {
var_dump($var);
var_dump($value);
}
}
}
}
using it
DebugHelper::printVarNames(
$systemDefinedVars = get_defined_vars(),
$varNames=array('yourVar00', 'yourVar01')
);
You could use compact() to achieve this.
$FooBar = "a string";
$newArray = compact('FooBar');
This would create an associative array with the variable name as the key. You could then loop through the array using the key name where you needed it.
foreach($newarray as $key => $value) {
echo $key;
}
I think you want to know variable name with it's value. You can use an associative array to achieve this.
use variable names for array keys:
$vars = array('FooBar' => 'a string');
When you want to get variable names, use array_keys($vars), it will return an array of those variable names that used in your $vars array as it's keys.
This is the way I did it
function getVar(&$var) {
$tmp = $var; // store the variable value
$var = '_$_%&33xc$%^*7_r4'; // give the variable a new unique value
$name = array_search($var, $GLOBALS); // search $GLOBALS for that unique value and return the key(variable)
$var = $tmp; // restore the variable old value
return $name;
}
Usage
$city = "San Francisco";
echo getVar($city); // city
Note: some PHP 7 versions will not work properly due to a bug in array_search with $GLOBALS, however all other versions will work.
See this https://3v4l.org/UMW7V
There is no predefined function in PHP that can output the name of a variable. However, you can use the result of get_defined_vars(), which returns all the variables defined in the scope, including name and value. Here is an example:
<?php
// Function for determining the name of a variable
function getVarName(&$var, $definedVars=null) {
$definedVars = (!is_array($definedVars) ? $GLOBALS : $definedVars);
$val = $var;
$rand = 1;
while (in_array($rand, $definedVars, true)) {
$rand = md5(mt_rand(10000, 1000000));
}
$var = $rand;
foreach ($definedVars as $dvName=>$dvVal) {
if ($dvVal === $rand) {
$var = $val;
return $dvName;
}
}
return null;
}
// the name of $a is to be determined.
$a = 1;
// Determine the name of $a
echo getVarName($a);
?>
Read more in How to get a variable name as a string in PHP?
Why don't you just build a simple function and TELL it?
/**
* Prints out $obj for debug
*
* #param any_type $obj
* #param (string) $title
*/
function print_all( $obj, $title = false )
{
print "\n<div style=\"font-family:Arial;\">\n";
if( $title ) print "<div style=\"background-color:red; color:white; font-size:16px; font-weight:bold; margin:0; padding:10px; text-align:center;\">$title</div>\n";
print "<pre style=\"background-color:yellow; border:2px solid red; color:black; margin:0; padding:10px;\">\n\n";
var_export( $obj );
print "\n\n</pre>\n</div>\n";
}
print_all( $aUser, '$aUser' );
I was looking for this but just decided to pass the name in, I usually have the name in the clipboard anyway.
function VarTest($my_var,$my_var_name){
echo '$'.$my_var_name.': '.$my_var.'<br />';
}
$fruit='apple';
VarTest($fruit,'fruit');
I know this is old and already answered but I was actually looking for this. I am posting this answer to save people a little time refining some of the answers.
Option 1:
$data = array('$FooBar');
$vars = [];
$vars = preg_replace('/^\\$/', '', $data);
$varname = key(compact($vars));
echo $varname;
Prints:
FooBar
For whatever reason you would find yourself in a situation like this, it does actually work.
.
Option 2:
$FooBar = "a string";
$varname = trim(array_search($FooBar, $GLOBALS), " \t.");
echo $varname;
If $FooBar holds a unique value, it will print 'FooBar'. If $FooBar is empty or null it will print the name of the first empty or null string it finds.
It could be used as such:
if (isset($FooBar) && !is_null($FooBar) && !empty($FooBar)) {
$FooBar = "a string";
$varname = trim(array_search($FooBar, $GLOBALS), " \t.");
}
other use:
shrug
function varsToArrayAssoc(...$arguments){
$bt = debug_backtrace();
$file = file($bt[0]['file']);
$src = $file[$bt[0]['line']-1];
$pat = '#(.*)'.__FUNCTION__.' *?\( *?(.*) *?\)(.*)#i';
$vars =explode(',',substr_replace(trim(preg_replace($pat, '$2', $src)) ,"", -1));
$result=[];
foreach(func_get_args() as $key=>$v){
$index=trim(explode('$',$vars[$key])[1]);
$result[$index]=$v;
}
return $result;
}
$a=12;
$b=13;
$c=123;
$d='aa';
var_dump(varsToArrayAssoc($a,$b,$c,$d));
Use this to detach user variables from global to check variable at the moment.
function get_user_var_defined ()
{
return array_slice($GLOBALS,8,count($GLOBALS)-8);
}
function get_var_name ($var)
{
$vuser = get_user_var_defined();
foreach($vuser as $key=>$value)
{
if($var===$value) return $key ;
}
}
It may be considered quick and dirty, but my own personal preference is to use a function/method like this:
public function getVarName($var) {
$tmp = array($var => '');
$keys = array_keys($tmp);
return trim($keys[0]);
}
basically it just creates an associative array containing one null/empty element, using as a key the variable for which you want the name.
we then get the value of that key using array_keys and return it.
obviously this gets messy quick and wouldn't be desirable in a production environment, but it works for the problem presented.
why we have to use globals to get variable name... we can use simply like below.
$variableName = "ajaxmint";
echo getVarName('$variableName');
function getVarName($name) {
return str_replace('$','',$name);
}
I really fail to see the use case... If you will type print_var_name($foobar) what's so hard (and different) about typing print("foobar") instead?
Because even if you were to use this in a function, you'd get the local name of the variable...
In any case, here's the reflection manual in case there's something you need in there.

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