php 检查并返回重复数组php
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Check and return duplicates array php
提问by NVG
I would like to check if my array has any duplicates and return the duplicated values in an array. I want this to be as efficient as possible.
我想检查我的数组是否有任何重复项并返回数组中的重复值。我希望这尽可能高效。
Example :$array = array(1,2,2,4,5)
function returndup($array) should return 2 ;
if array is array(1,2,1,2,5);
it should return an array with 1,2
Also the initial array is always 5 positions long
此外，初始数组始终为 5 个位置
回答by user187291
this will be ~100 times faster than array_diff
这将比 array_diff 快约 100 倍
$dups = array();
foreach(array_count_values($arr) as $val => $c)
if($c > 1) $dups[] = $val;
回答by Gumbo
You can get the difference of the original array and a copy without duplicates using array_uniqueand array_diff_assoc:
您可以使用array_uniqueand获得原始数组和没有重复的副本的差异 array_diff_assoc：
array_diff_assoc($arr, array_unique($arr))
回答by JAL
function array_dup($ar){
return array_unique(array_diff_assoc($ar,array_unique($ar)));
}
Should do the trick.
应该做的伎俩。
回答by JAL
You can do like this:
你可以这样做：
function showDups($array)
{
$array_temp = array();
foreach($array as $val)
{
if (!in_array($val, $array_temp))
{
$array_temp[] = $val;
}
else
{
echo 'duplicate = ' . $val . '<br />';
}
}
}
$array = array(1,2,2,4,5);
showDups($array);
Output:
输出：
duplicate = 2
回答by faebser
in addition to gumbo's answer:
除了秋葵汤的回答：
function returndup($arr)
{
return array_diff_key($arr, array_unique($arr));
}
回答by Ronn0
function returndup($array)
{
$results = array();
$duplicates = array();
foreach ($array as $item) {
if (in_array($item, $results)) {
$duplicates[] = $item;
}
$results[] = $item;
}
return $duplicates;
}
回答by Stefan Gabos
I did some tests and indeed @user187291's variant is the fastest. But, it turns out that @Gumbo's and @faebser's alternative are almost as fast, @faebser's being just slightly faster than @Gumbo's and sometimes even fastest of all.
我做了一些测试，确实@user187291 的变体是最快的。但是，事实证明@Gumbo 和@faebser 的替代方案几乎一样快，@faebser 仅比@Gumbo 稍快，有时甚至是最快的。
Here's the code I used
这是我使用的代码
$array = array(1, "hello", 1, "world", "hello");
$times = 1000000;
$start = microtime(true);
for ($i = 0; $i < $times; $i++) {
$dups = array();
foreach(array_count_values($array) as $val => $c)
if( $c > 1) $dups[] = $val;
}
$end = microtime(true);
echo 'variant 1 (user187291): ' . ($end - $start);
echo '<br><br><br>';
$start = microtime(true);
for ($i = 0; $i < $times; $i++)
$dups = array_unique(array_diff_assoc($array, array_unique($array)));
$end = microtime(true);
echo 'variant 2 (JAL): ' . ($end - $start);
echo '<br><br><br>';
$start = microtime(true);
for ($i = 0; $i < $times; $i++)
$dups = array_diff_assoc($array, array_unique($array));
$end = microtime(true);
echo 'variant 3 (Gumbo): ' . ($end - $start);
echo '<br><br><br>';
$start = microtime(true);
for ($i = 0; $i < $times; $i++)
$dups = array_diff_key($array, array_unique($array));
$end = microtime(true);
echo 'variant 4 (faebser): ' . ($end - $start);
echo '<br><br><br>';
回答by Nemo
I have found another way to return duplicates in an array
我找到了另一种返回数组中重复项的方法
function printRepeating($arr, $size)
{
$i;
$j;
for($i = 0; $i < $size; $i++)
for($j = $i + 1; $j < $size; $j++)
if($arr[$i] == $arr[$j])
echo $arr[$i], " ";
}
printRepeating($array, sizeof($array,0);
回答by raviranjan prasad
$duplicate_array = array();
$duplicate_array = array();
for($i=0;$i<count($array);$i++){
for($j=0;$j<count($array);$j++){
if($i != $j && $array[$i] == $array[$j]){
if(!in_array($array[$j], $duplicate_array)){
$duplicate_array[] = $array[$j];
}
}
}
}
