How to check whether an array is empty using PHP?
players will either be empty or a comma separated list (or a single value). What is the easiest way to check if it's empty? I'm assuming I can do so as soon as I fetch the $gameresult array into $gamerow? In this case it would probably be more efficient to skip exploding the $playerlist if it's empty, but for the sake of argument, how would I check if an array is empty as well?
$gamerow = mysql_fetch_array($gameresult);
$playerlist = explode(",", $gamerow['players']开发者_开发技巧);
If you just need to check if there are ANY elements in the array, you can use either the array itself, due to PHP's loose typing, or - if you prefer a stricter approach - use count():
if (!$playerlist) {
// list is empty.
}
if (count($playerlist) === 0) {
// list is empty.
}
If you need to clean out empty values before checking (generally done to prevent explodeing weird strings):
foreach ($playerlist as $key => $value) {
if (!strlen($value)) {
unset($playerlist[$key]);
}
}
if (!$playerlist) {
//empty array
}
An empty array is falsey in PHP, so you don't even need to use empty() as others have suggested.
<?php
$playerList = array();
if (!$playerList) {
echo "No players";
} else {
echo "Explode stuff...";
}
// Output is: No players
PHP's empty() determines if a variable doesn't exist or has a falsey value (like array(), 0, null, false, etc).
In most cases you just want to check !$emptyVar. Use empty($emptyVar) if the variable might not have been set AND you don't wont to trigger an E_NOTICE; IMO this is generally a bad idea.
Some decent answers, but just thought I'd expand a bit to explain more clearly when PHP determines if an array is empty.
Main Notes:
An array with a key (or keys) will be determined as NOT empty by PHP.
As array values need keys to exist, having values or not in an array doesn't determine if it's empty, only if there are no keys (AND therefore no values).
So checking an array with empty() doesn't simply tell you if you have values or not, it tells you if the array is empty, and keys are part of an array.
So consider how you are producing your array before deciding which checking method to use.
EG An array will have keys when a user submits your HTML form when each form field has an array name (ie name="array[]").
A non empty array will be produced for each field as there will be auto incremented key values for each form field's array.
Take these arrays for example:
/* Assigning some arrays */
// Array with user defined key and value
$ArrayOne = array("UserKeyA" => "UserValueA", "UserKeyB" => "UserValueB");
// Array with auto increment key and user defined value
// as a form field would return with user input
$ArrayTwo[] = "UserValue01";
$ArrayTwo[] = "UserValue02";
// Array with auto incremented key and no value
// as a form field would return without user input
$ArrayThree[] = '';
$ArrayThree[] = '';
If you echo out the array keys and values for the above arrays, you get the following:
ARRAY ONE:
[UserKeyA] => [UserValueA]
[UserKeyB] => [UserValueB]ARRAY TWO:
[0] => [UserValue01]
[1] => [UserValue02]ARRAY THREE:
[0] => []
[1] => []
And testing the above arrays with empty() returns the following results:
ARRAY ONE:
$ArrayOne is not emptyARRAY TWO:
$ArrayTwo is not emptyARRAY THREE:
$ArrayThree is not empty
An array will always be empty when you assign an array but don't use it thereafter, such as:
$ArrayFour = array();
This will be empty, ie PHP will return TRUE when using if empty() on the above.
So if your array has keys - either by eg a form's input names or if you assign them manually (ie create an array with database column names as the keys but no values/data from the database), then the array will NOT be empty().
In this case, you can loop the array in a foreach, testing if each key has a value. This is a good method if you need to run through the array anyway, perhaps checking the keys or sanitising data.
However it is not the best method if you simply need to know "if values exist" returns TRUE or FALSE. There are various methods to determine if an array has any values when it's know it will have keys. A function or class might be the best approach, but as always it depends on your environment and exact requirements, as well as other things such as what you currently do with the array (if anything).
Here's an approach which uses very little code to check if an array has values:
Using array_filter():
Iterates over each value in the array passing them to the callback function. If the callback function returns true, the current value from array is returned into the result array. Array keys are preserved.
$EmptyTestArray = array_filter($ArrayOne);
if (!empty($EmptyTestArray))
{
// do some tests on the values in $ArrayOne
}
else
{
// Likely not to need an else,
// but could return message to user "you entered nothing" etc etc
}
Running array_filter() on all three example arrays (created in the first code block in this answer) results in the following:
ARRAY ONE:
$arrayone is not emptyARRAY TWO:
$arraytwo is not emptyARRAY THREE:
$arraythree is empty
So when there are no values, whether there are keys or not, using array_filter() to create a new array and then check if the new array is empty shows if there were any values in the original array.
It is not ideal and a bit messy, but if you have a huge array and don't need to loop through it for any other reason, then this is the simplest in terms of code needed.
I'm not experienced in checking overheads, but it would be good to know the differences between using array_filter() and foreach checking if a value is found.
Obviously benchmark would need to be on various parameters, on small and large arrays and when there are values and not etc.
count($gamerow['players']) will be 0.
I ran the benchmark included at the end of the post. To compare the methods:
count($arr) == 0: countempty($arr): empty$arr == []: comp(bool) $arr: cast
and got the following results
Contents \method | count | empty | comp | cast |
------------------|--------------|--------------|--------------|--------------|
Empty |/* 1.213138 */|/* 1.070011 */|/* 1.628529 */| 1.051795 |
Uniform |/* 1.206680 */| 1.047339 |/* 1.498836 */|/* 1.052737 */|
Integer |/* 1.209668 */|/* 1.079858 */|/* 1.486134 */| 1.051138 |
String |/* 1.242137 */| 1.049148 |/* 1.630259 */|/* 1.056610 */|
Mixed |/* 1.229072 */|/* 1.068569 */|/* 1.473339 */| 1.064111 |
Associative |/* 1.206311 */| 1.053642 |/* 1.480637 */|/* 1.137740 */|
------------------|--------------|--------------|--------------|--------------|
Total |/* 7.307005 */| 6.368568 |/* 9.197733 */|/* 6.414131 */|
The difference between empty and casting to a boolean are insignificant. I've run this test multiple times and they appear to be essentially equivalent. The contents of the arrays do not seem to play a significant role. The two produce the opposite results but the logical negation is barely enough to push casting to winning most of the time so I personally prefer empty for the sake of legibility in either case.
#!/usr/bin/php
<?php
// 012345678
$nt = 90000000;
$arr0 = [];
$arr1 = [];
$arr2 = [];
$arr3 = [];
$arr4 = [];
$arr5 = [];
for ($i = 0; $i < 500000; $i++) {
$arr1[] = 0;
$arr2[] = $i;
$arr3[] = md5($i);
$arr4[] = $i % 2 ? $i : md5($i);
$arr5[md5($i)] = $i;
}
$t00 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
count($arr0) == 0;
}
$t01 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
empty($arr0);
}
$t02 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
$arr0 == [];
}
$t03 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
(bool) $arr0;
}
$t04 = microtime(true);
$t10 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
count($arr1) == 0;
}
$t11 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
empty($arr1);
}
$t12 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
$arr1 == [];
}
$t13 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
(bool) $arr1;
}
$t14 = microtime(true);
/* ------------------------------ */
$t20 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
count($arr2) == 0;
}
$t21 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
empty($arr2);
}
$t22 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
$arr2 == [];
}
$t23 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
(bool) $arr2;
}
$t24 = microtime(true);
/* ------------------------------ */
$t30 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
count($arr3) == 0;
}
$t31 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
empty($arr3);
}
$t32 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
$arr3 == [];
}
$t33 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
(bool) $arr3;
}
$t34 = microtime(true);
/* ------------------------------ */
$t40 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
count($arr4) == 0;
}
$t41 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
empty($arr4);
}
$t42 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
$arr4 == [];
}
$t43 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
(bool) $arr4;
}
$t44 = microtime(true);
/* ----------------------------------- */
$t50 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
count($arr5) == 0;
}
$t51 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
empty($arr5);
}
$t52 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
$arr5 == [];
}
$t53 = microtime(true);
for ($i = 0; $i < $nt; $i++) {
(bool) $arr5;
}
$t54 = microtime(true);
/* ----------------------------------- */
$t60 = $t00 + $t10 + $t20 + $t30 + $t40 + $t50;
$t61 = $t01 + $t11 + $t21 + $t31 + $t41 + $t51;
$t62 = $t02 + $t12 + $t22 + $t32 + $t42 + $t52;
$t63 = $t03 + $t13 + $t23 + $t33 + $t43 + $t53;
$t64 = $t04 + $t14 + $t24 + $t34 + $t44 + $t54;
/* ----------------------------------- */
$ts0[1] = number_format(round($t01 - $t00, 6), 6);
$ts0[2] = number_format(round($t02 - $t01, 6), 6);
$ts0[3] = number_format(round($t03 - $t02, 6), 6);
$ts0[4] = number_format(round($t04 - $t03, 6), 6);
$min_idx = array_keys($ts0, min($ts0))[0];
foreach ($ts0 as $idx => $val) {
if ($idx == $min_idx) {
$ts0[$idx] = " $val ";
} else {
$ts0[$idx] = "/* $val */";
}
}
$ts1[1] = number_format(round($t11 - $t10, 6), 6);
$ts1[2] = number_format(round($t12 - $t11, 6), 6);
$ts1[3] = number_format(round($t13 - $t12, 6), 6);
$ts1[4] = number_format(round($t14 - $t13, 6), 6);
$min_idx = array_keys($ts1, min($ts1))[0];
foreach ($ts1 as $idx => $val) {
if ($idx == $min_idx) {
$ts1[$idx] = " $val ";
} else {
$ts1[$idx] = "/* $val */";
}
}
$ts2[1] = number_format(round($t21 - $t20, 6), 6);
$ts2[2] = number_format(round($t22 - $t21, 6), 6);
$ts2[3] = number_format(round($t23 - $t22, 6), 6);
$ts2[4] = number_format(round($t24 - $t23, 6), 6);
$min_idx = array_keys($ts2, min($ts2))[0];
foreach ($ts2 as $idx => $val) {
if ($idx == $min_idx) {
$ts2[$idx] = " $val ";
} else {
$ts2[$idx] = "/* $val */";
}
}
$ts3[1] = number_format(round($t31 - $t30, 6), 6);
$ts3[2] = number_format(round($t32 - $t31, 6), 6);
$ts3[3] = number_format(round($t33 - $t32, 6), 6);
$ts3[4] = number_format(round($t34 - $t33, 6), 6);
$min_idx = array_keys($ts3, min($ts3))[0];
foreach ($ts3 as $idx => $val) {
if ($idx == $min_idx) {
$ts3[$idx] = " $val ";
} else {
$ts3[$idx] = "/* $val */";
}
}
$ts4[1] = number_format(round($t41 - $t40, 6), 6);
$ts4[2] = number_format(round($t42 - $t41, 6), 6);
$ts4[3] = number_format(round($t43 - $t42, 6), 6);
$ts4[4] = number_format(round($t44 - $t43, 6), 6);
$min_idx = array_keys($ts4, min($ts4))[0];
foreach ($ts4 as $idx => $val) {
if ($idx == $min_idx) {
$ts4[$idx] = " $val ";
} else {
$ts4[$idx] = "/* $val */";
}
}
$ts5[1] = number_format(round($t51 - $t50, 6), 6);
$ts5[2] = number_format(round($t52 - $t51, 6), 6);
$ts5[3] = number_format(round($t53 - $t52, 6), 6);
$ts5[4] = number_format(round($t54 - $t53, 6), 6);
$min_idx = array_keys($ts5, min($ts5))[0];
foreach ($ts5 as $idx => $val) {
if ($idx == $min_idx) {
$ts5[$idx] = " $val ";
} else {
$ts5[$idx] = "/* $val */";
}
}
$ts6[1] = number_format(round($t61 - $t60, 6), 6);
$ts6[2] = number_format(round($t62 - $t61, 6), 6);
$ts6[3] = number_format(round($t63 - $t62, 6), 6);
$ts6[4] = number_format(round($t64 - $t63, 6), 6);
$min_idx = array_keys($ts6, min($ts6))[0];
foreach ($ts6 as $idx => $val) {
if ($idx == $min_idx) {
$ts6[$idx] = " $val ";
} else {
$ts6[$idx] = "/* $val */";
}
}
echo " | count | empty | comp | cast |\n";
echo "-------------|--------------|--------------|--------------|--------------|\n";
echo " Empty |";
echo $ts0[1] . '|';
echo $ts0[2] . '|';
echo $ts0[3] . '|';
echo $ts0[4] . "|\n";
echo " Uniform |";
echo $ts1[1] . '|';
echo $ts1[2] . '|';
echo $ts1[3] . '|';
echo $ts1[4] . "|\n";
echo " Integer |";
echo $ts2[1] . '|';
echo $ts2[2] . '|';
echo $ts2[3] . '|';
echo $ts2[4] . "|\n";
echo " String |";
echo $ts3[1] . '|';
echo $ts3[2] . '|';
echo $ts3[3] . '|';
echo $ts3[4] . "|\n";
echo " Mixed |";
echo $ts4[1] . '|';
echo $ts4[2] . '|';
echo $ts4[3] . '|';
echo $ts4[4] . "|\n";
echo " Associative |";
echo $ts5[1] . '|';
echo $ts5[2] . '|';
echo $ts5[3] . '|';
echo $ts5[4] . "|\n";
echo "-------------|--------------|--------------|--------------|--------------|\n";
echo " Total |";
echo $ts6[1] . '|';
echo $ts6[2] . '|';
echo $ts6[3] . '|';
echo $ts6[4] . "|\n";
If you'd like to exclude the false or empty rows (such as 0 => ''), where using empty() will fail, you can try:
if (array_filter($playerlist) == []) {
// Array is empty!
}
array_filter(): If no callback is supplied, all entries of array equal to FALSE (see converting to boolean) will be removed.
If you'd like to remove all NULL, FALSE and empty strings (''), but leave zero values (0), you can use strlen as a callback, e.g.:
$is_empty = array_filter($playerlist, 'strlen') == [];
If you want to ascertain whether the variable you are testing is actually explicitly an empty array, you could use something like this:
if ($variableToTest === array()) {
echo 'this is explicitly an empty array!';
}
Why has no one said this answer:
$array = [];
if($array == []) {
// array is empty
}
is_array($detect) && empty($detect);
is_array
if you are to check the array content you may use:
$arr = array();
if(!empty($arr)){
echo "not empty";
}
else
{
echo "empty";
}
see here: http://codepad.org/EORE4k7v
In my opinion the simplest way for an indexed array would be simply:
if ($array) {
//Array is not empty...
}
An 'if' condition on the array would evaluate to true if the array is not empty and false if the array is empty. This is not applicable to associative arrays.
I use this code
$variable = array();
if( count( $variable ) == 0 )
{
echo "Array is Empty";
}
else
{
echo "Array is not Empty";
}
But note that if the array has a large number of keys, this code will spend much time counting them, as compared to the other answers here.
You can use array_filter() which works great for all situations:
$ray_state = array_filter($myarray);
if (empty($ray_state)) {
echo 'array is empty';
} else {
echo 'array is not empty';
}
Making the most appropriate decision requires knowing the quality of your data and what processes are to follow.
- If you are going to disqualify/disregard/remove this row, then the earliest point of filtration should be in the mysql query.
WHERE players IS NOT NULLWHERE players != ''WHERE COALESCE(players, '') != ''WHERE players IS NOT NULL AND players != ''- ...it kind of depends on your store data and there will be other ways, I'll stop here.
If you aren't 100% sure if the column will exist in the result set, then you should check that the column is declared. This will mean calling
array_key_exists(),isset(), orempty()on the column. I am not going to bother delineating the differences here (there are other SO pages for that breakdown, here's a start: 1, 2, 3). That said, if you aren't in total control of the result set, then maybe you have over-indulged application "flexibility" and should rethink if the trouble of potentially accessing non-existent column data is worth it. Effectively, I am saying that you should never need to check if a column is declared -- ergo you should never needempty()for this task. If anyone is arguing thatempty()is more appropriate, then they are pushing their own personal opinion about expressiveness of scripting. If you find the condition in #5 below to be ambiguous, add an inline comment to your code -- but I wouldn't. The bottom line is that there is no programmatical advantage to making the function call.Might your string value contain a
0that you want to deem true/valid/non-empty? If so, then you only need to check if the column value has length.
Here is a Demo using strlen(). This will indicated whether or not the string will create meaningful array elements if exploded.
I think it is important to mention that by unconditionally exploding, you are GUARANTEED to generate a non-empty array. Here's proof: Demo In other words, checking if the array is empty is completely useless -- it will be non-empty every time.
If your string will NOT POSSIBLY contain a zero value (because, say, this is a csv consisting of ids which start from
1and only increment), thenif ($gamerow['players']) {is all you need -- end of story....but wait, what are you doing after determining the emptiness of this value? If you have something down-script that is expecting
$playerlist, but you are conditionally declaring that variable, then you risk using the previous row's value or again generating Notices. So do you need to unconditionally declare$playerlistas something? If there are no truthy values in the string, does your application benefit from declaring an empty array? Chances are, the answer is yes. In this case, you can ensure that the variable is array-type by falling back to an empty array -- this way it won't matter if you feed that variable into a loop. The following conditional declarations are all equivalent.
if ($gamerow['players']) { $playerlist = explode(',', $gamerow['players']); } else { $playerlist = []; }$playerlist = $gamerow['players'] ? explode(',', $gamerow['players']) : [];
Why have I gone to such length to explain this very basic task?
- I have whistleblown nearly every answer on this page and this answer is likely to draw revenge votes (this happens often to whistleblowers who defend this site -- if an answer has downvotes and no comments, always be skeptical).
- I think it is important that Stackoverflow is a trusted resource that doesn't poison researchers with misinformation and suboptimal techniques.
- This is how I show how much I care about upcoming developers so that they learn the how and the why instead of just spoon-feeding a generation of copy-paste programmers.
- I frequently use old pages to close new duplicate pages -- this is the responsibility of veteran volunteers who know how to quickly find duplicates. I cannot bring myself to use an old page with bad/false/suboptimal/misleading information as a reference because then I am actively doing a disservice to a new researcher.
empty($gamerow['players'])
I think the best way to determine if the array is empty or not is to use count() like so:
if(count($array)) {
return 'anything true goes here';
}else {
return 'anything false';
}
You can use the following php functions to check whether an array is empty or not
Using empty() function
$variable = array();
if(empty($variable)){
echo("The array is empty.");
}
OUTPUT: The array is empty
Using sizeof() function
$variable = array();
$arraysize = sizeof($variable);
echo("The size of the array is $arraysize. \n");
if(sizeof($variable) == 0)
echo("The array is empty.");
OUTPUT:
The size of the array is 0.
The array is empty.
$gamerow = mysql_fetch_array($gameresult);
if (!empty(($gamerow['players'])) {
$playerlist = explode(",", $gamerow['players']);
}else{
// do stuff if array is empty
}
I won't repeat what has already been said here, just tested and the more efficient way on PHP-7.3 is !empty($myARR) or isset($myARR[0]), both shows same speed. Anything else is pretty slower, including array_key_exists($myARR[0]) and just comparing $myARR !== Array() | $myARR !== []. So, I prefer empty(), simple and fast.
$status = "";
$new_array = array();
if(!empty($new_array)){
$status = "1"; // not a blank array
}
else{
$status = "0"; // blank array
}
Many options have been discussed already to check if an array is empty or does not contains a value, as there are
if ($playerlist) {}
if (!empty($playerlist)) {}
if (count($playerlist) > 0) {}
All have their pros and cons.
But there is another option, that might be feasable if you are sure, that your array has numeric keys only, starting from zero (i.e. this happens if you explode() a string):
if (isset($playerlist[0])) {
// do something
}
This is even a bit faster than the other solutions.
array_filter recursive and count
function array_filter_recursive(array $arr)
{
array_walk($arr,function(&$item){if (is_array($item)) { $item = array_filter_recursive($item);}});
return array_filter($arr);
}
function is_empty_array(array $arr):bool{
return count(array_filter_recursive($arr)) == 0;
}
test
$c=['b'=>2,'c'=>3];
$a=[];
$b=[[]];
$d=['a'=>[]];
$e=['a'=>[],[]];
$f=['a'=>[[],[],[]],[]];
$g=[[[],[[],[[],[[],[]]]]],[]];
$i=[[[],[[],[[],[[],['s'=>1]]]]],[]];
var_dump(is_empty_array($c));//false
var_dump(is_empty_array($a));//true
var_dump(is_empty_array($b));//true
var_dump(is_empty_array($d));//true
var_dump(is_empty_array($e));//true
var_dump(is_empty_array($f));//true
var_dump(is_empty_array($g));//true
var_dump(is_empty_array($i));//false
I have solved this issue with following code.
$catArray=array();
$catIds=explode(',',$member['cat_id']);
if(!empty($catIds[0])){
foreach($catIds as $cat_id){
$catDetail=$this->Front_Category->get_category_detail($cat_id);
$catArray[]=$catDetail['allData']['cat_title'];
}
echo implode(',',$catArray);
}
This seems working for all cases
if(!empty(sizeof($array)))
加载中,请稍侯......
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