blocks|key|350909|text|您可以使用array_intersect()。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|350910|$result+=+!empty(array_intersect($people,+$criminals));|code-block|syntax|javascript|350911|entityMap|0|LINK|mutability|MUTABLE|url|http://www.php.net/array_intersect^0|5|H|5|H|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

You can use <a href="http://www.php.net/array_intersect" rel="noreferrer"><code>array_intersect()</code></a>.

<pre><code>$result = !empty(array_intersect($people, $criminals));
</code></pre>

blocks|key|349925|text|使用array_intersect()和count()+(而不是empty)没有什么问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|349926|例如：|349927|$bFound+=+(count(array_intersect($criminals,+$people)))+?+true+:+false;|code-block|syntax|javascript|349928|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

There's little wrong with using array_intersect() and count() (instead of empty).

For example:

<pre><code>$bFound = (count(array_intersect($criminals, $people))) ? true : false;
</code></pre>

blocks|key|3342749|text|如果'empty‘不是最好的选择，那么如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3342750|if+(array_intersect($people,+$criminals))+{...}+//when+found|code-block|syntax|javascript|3342751|或|3342752|if+(!array_intersect($people,+$criminals))+{...}+//when+not+found|3342753|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

if 'empty' is not the best choice, what about this:

<pre><code>if (array_intersect($people, $criminals)) {...} //when found
</code></pre>

or

<pre><code>if (!array_intersect($people, $criminals)) {...} //when not found
</code></pre>

blocks|key|348536|text|该代码无效，因为您只能将变量传递到语言构造中。empty()是一种语言构造。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|348537|您必须在两行代码中完成此操作：|348538|$result+=+array_intersect($people,+$criminals);
$result+=+!empty($result);|code-block|syntax|javascript|348539|entityMap^0|N|7|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|R|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|S|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

That code is invalid as you can only pass variables into language constructs. <code>empty()</code> is a language construct.

You have to do this in two lines:

<pre><code>$result = array_intersect($people, $criminals);
$result = !empty($result);
</code></pre>

blocks|key|3129916|text|in_array与array_intersect的性能测试：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3129917|$a1+=+array(2,4,8,11,12,13,14,15,16,17,18,19,20);

$a2+=+array(3,20);

$intersect_times+=+array();
$in_array_times+=+array();
for($j+=+0;+$j+<+10;+$j%2B%2B)
{
++++/*****+TEST+ONE+array_intersect+*******/
++++$t+=+microtime(true);
++++for($i+=+0;+$i+<+100000;+$i%2B%2B)
++++{
++++++++$x+=+array_intersect($a1,$a2);
++++++++$x+=+empty($x);
++++}
++++$intersect_times[]+=+microtime(true)+-+$t;


++++/*****+TEST+TWO+in_array+*******/
++++$t2+=+microtime(true);
++++for($i+=+0;+$i+<+100000;+$i%2B%2B)
++++{
++++++++$x+=+false;
++++++++foreach($a2+as+$v){
++++++++++++if(in_array($v,$a1))
++++++++++++{
++++++++++++++++$x+=+true;
++++++++++++++++break;
++++++++++++}
++++++++}
++++}
++++$in_array_times[]+=+microtime(true)+-+$t2;
}

echo+'<hr> '.implode(' ',$intersect_times).' array_intersect+avg:+'.(array_sum($intersect_times)+/+count($intersect_times));
echo+'<hr> '.implode(' ',$in_array_times).' in_array+avg:+'.(array_sum($in_array_times)+/+count($in_array_times));
exit;|code-block|syntax|javascript|3129918|结果如下：|3129919|0.26520013809204
0.15600109100342
0.15599989891052
0.15599989891052
0.1560001373291
0.1560001373291
0.15599989891052
0.15599989891052
0.15599989891052
0.1560001373291
array_intersect+avg:+0.16692011356354

0.015599966049194
0.031199932098389
0.031200170516968
0.031199932098389
0.031200885772705
0.031199932098389
0.031200170516968
0.031201124191284
0.031199932098389
0.031199932098389
in_array+avg:+0.029640197753906|3129920|in_array的速度至少快5倍。请注意，一旦找到结果，我们就“中断”。|3129921|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Performance test for in_array vs array_intersect:

<pre><code>$a1 = array(2,4,8,11,12,13,14,15,16,17,18,19,20);

$a2 = array(3,20);

$intersect_times = array();
$in_array_times = array();
for($j = 0; $j &lt; 10; $j++)
{
 /***** TEST ONE array_intersect *******/
 $t = microtime(true);
 for($i = 0; $i &lt; 100000; $i++)
 {
 $x = array_intersect($a1,$a2);
 $x = empty($x);
 }
 $intersect_times[] = microtime(true) - $t;


 /***** TEST TWO in_array *******/
 $t2 = microtime(true);
 for($i = 0; $i &lt; 100000; $i++)
 {
 $x = false;
 foreach($a2 as $v){
 if(in_array($v,$a1))
 {
 $x = true;
 break;
 }
 }
 }
 $in_array_times[] = microtime(true) - $t2;
}

echo '&lt;hr&gt;&lt;br&gt;'.implode('&lt;br&gt;',$intersect_times).'&lt;br&gt;array_intersect avg: '.(array_sum($intersect_times) / count($intersect_times));
echo '&lt;hr&gt;&lt;br&gt;'.implode('&lt;br&gt;',$in_array_times).'&lt;br&gt;in_array avg: '.(array_sum($in_array_times) / count($in_array_times));
exit;
</code></pre>

Here are the results:

<pre><code>0.26520013809204
0.15600109100342
0.15599989891052
0.15599989891052
0.1560001373291
0.1560001373291
0.15599989891052
0.15599989891052
0.15599989891052
0.1560001373291
array_intersect avg: 0.16692011356354

0.015599966049194
0.031199932098389
0.031200170516968
0.031199932098389
0.031200885772705
0.031199932098389
0.031200170516968
0.031201124191284
0.031199932098389
0.031199932098389
in_array avg: 0.029640197753906
</code></pre>

in_array is at least 5 times faster. Note that we "break" as soon as a result is found.

blocks|key|3129890|text|您还可以按如下方式使用in_array：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3129891|<?php
$found+=+null;
$people+=+array(3,20,2);
$criminals+=+array(+2,+4,+8,+11,+12,+13,+14,+15,+16,+17,+18,+19,+20);
foreach($people+as+$num)+{
++++if+(in_array($num,$criminals))+{
++++++++$found[$num]+=+true;
++++}+
}
var_dump($found);
//+array(2)+{+[20]=>+bool(true)+++[2]=>+bool(true)+}|code-block|syntax|javascript|3129892|虽然array_intersect的使用肯定更方便，但事实证明，它在性能方面并不是真正优越。我也创建了这个脚本：|3129893|<?php
$found+=+null;
$people+=+array(3,20,2);
$criminals+=+array(+2,+4,+8,+11,+12,+13,+14,+15,+16,+17,+18,+19,+20);
$fastfind+=+array_intersect($people,$criminals);
var_dump($fastfind);
//+array(2)+{+[1]=>+int(20)+++[2]=>+int(2)+}|3129894|然后，我分别在：http://3v4l.org/WGhO7/perf#tabs和http://3v4l.org/g1Hnu/perf#tabs上运行了这两个代码片段，并检查了它们的性能。有趣的是，PHP5.6的总CPU时间，即用户时间%2B系统时间是相同的，内存也是相同的。在PHP5.4下，in_array的总CPU时间比array_intersect少，尽管略有减少。|offset|length|3129895|entityMap|0|LINK|mutability|MUTABLE|url|http://3v4l.org/WGhO7/perf#tabs|1|http://3v4l.org/g1Hnu/perf#tabs^0|0|0|0|0|8|V|0|14|V|1|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|10|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|12|8|@]|9|@$M|13|N|14|1|15]|$M|16|N|17|1|18]]|A|$]]|$1|O|3|-4|5|6|7|19|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]|W|$5|R|S|T|A|$U|X]]]]

You could also use in_array as follows:

<pre><code>&lt;?php
$found = null;
$people = array(3,20,2);
$criminals = array( 2, 4, 8, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20);
foreach($people as $num) {
 if (in_array($num,$criminals)) {
 $found[$num] = true;
 } 
}
var_dump($found);
// array(2) { [20]=&gt; bool(true) [2]=&gt; bool(true) }
</code></pre>

While array_intersect is certainly more convenient to use, it turns out that its not really superior in terms of performance. I created this script too:

<pre><code>&lt;?php
$found = null;
$people = array(3,20,2);
$criminals = array( 2, 4, 8, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20);
$fastfind = array_intersect($people,$criminals);
var_dump($fastfind);
// array(2) { [1]=&gt; int(20) [2]=&gt; int(2) }
</code></pre>

Then, I ran both snippets respectively at: <a href="http://3v4l.org/WGhO7/perf#tabs" rel="nofollow">http://3v4l.org/WGhO7/perf#tabs</a> and <a href="http://3v4l.org/g1Hnu/perf#tabs" rel="nofollow">http://3v4l.org/g1Hnu/perf#tabs</a> and checked the performance of each. The interesting thing is that the total CPU time, i.e. user time + system time is the same for PHP5.6 and the memory also is the same. The total CPU time under PHP5.4 is less for in_array than array_intersect, albeit marginally so.

blocks|key|3129940|text|这是我在研究了一段时间后的一种方法。我想创建一个Laravel+API端点来检查字段是否“正在使用”，因此重要的信息是:+1)哪个DB表?+2)哪个DB列？3)该列中是否有与搜索项匹配的值？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3129941|了解了这一点，我们可以构造我们的关联数组：|3129942|$SEARCHABLE_TABLE_COLUMNS+=+[
++++'users'+=>+[+'email'+],
];|code-block|syntax|javascript|3129943|然后，我们可以设置我们要检查的值：|3129944|$table+=+'users';
$column+=+'email';
$value+=+'alice@bob.com';|3129945|然后，我们可以使用array_key_exists()和in_array()来执行一个、两个步骤的组合，然后根据truthy条件执行操作：|offset|length|style|CODE|3129946|//+step+1:+check+if+'users'+exists+as+a+key+in+`$SEARCHABLE_TABLE_COLUMNS`
if+(array_key_exists($table,+$SEARCHABLE_TABLE_COLUMNS))+{

++++//+step+2:+check+if+'email'+is+in+the+array:+$SEARCHABLE_TABLE_COLUMNS[$table]
++++if+(in_array($column,+$SEARCHABLE_TABLE_COLUMNS[$table]))+{

++++++++//+if+table+and+column+are+allowed,+return+Boolean+if+value+already+exists
++++++++//+this+will+either+return+the+first+matching+record+or+null
++++++++$exists+=+DB::table($table)->where($column,+'=',+$value)->first();

++++++++if+($exists)+return+response()->json([+'in_use'+=>+true+],+200);
++++++++return+response()->json([+'in_use'+=>+false+],+200);
++++}

++++//+if+$column+isn't+in+$SEARCHABLE_TABLE_COLUMNS[$table],
++++//+then+we+need+to+tell+the+user+we+can't+proceed+with+their+request
++++return+response()->json([+'error'+=>+'Illegal+column+name:+'.$column+],+400);
}

//+if+$table+isn't+a+key+in+$SEARCHABLE_TABLE_COLUMNS,
//+then+we+need+to+tell+the+user+we+can't+proceed+with+their+request
return+response()->json([+'error'+=>+'Illegal+table+name:+'.$table+],+400);|3129947|我为特定于Laravel的PHP代码道歉，但我将其保留下来，因为我认为您可以将其作为伪代码阅读。的重要部分是两个同步执行的if语句。|3129948|3129949|、array_key_exists()和in_array()都是PHP函数。|blockquote|3129950|3129951|3129952|来源：|3129953|3129954|https://php.net/manual/en/function.array-key-exists.php|unordered-list-item|3129955|https://php.net/manual/en/function.in-array.php|3129956|3129957|我在上面展示的算法的优点是，您可以创建一个REST端点，比如GET+/in-use/{table}/{column}/{value}+(其中table、column和value都是变量)。|3129958|你可以：|3129959|$SEARCHABLE_TABLE_COLUMNS+=+[
++++'accounts'+=>+[+'account_name',+'phone',+'business_email'+],
++++'users'+=>+[+'email'+],
];|3129960|然后，您可以发出GET请求，例如：|3129961|GET+/in-use/accounts/account_name/Bob's+Drywall+(您可能需要对最后一部分进行uri编码，但通常不需要)|3129962|GET+/in-use/accounts/phone/888-555-1337|3129963|GET+/in-use/users/email/alice@bob.com|3129964|还请注意，没有人可以这样做：|3129965|GET+/in-use/users/password/dogmeat1337，因为您的user允许的列列表中没有列出password。|3129966|祝你旅途顺利。|3129967|entityMap|0|LINK|mutability|MUTABLE|url|1^0|0|0|0|0|0|9|I|S|A|1K|6|0|0|1P|2|0|0|1|I|K|A|0|0|0|0|0|0|1J|0|0|0|1B|1|0|0|U|10|1Y|5|24|6|2B|5|0|0|0|0|0|1B|0|0|13|0|0|11|0|0|0|12|17|4|1M|8|0|0^^$0|@$1|2|3|4|5|6|7|23|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|24|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|25|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|26|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|27|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|28|8|@$O|29|P|2A|Q|R]|$O|2B|P|2C|Q|R]|$O|2D|P|2E|Q|R]]|9|@]|A|$]]|$1|S|3|T|5|F|7|2F|8|@]|9|@]|A|$G|H]]|$1|U|3|V|5|6|7|2G|8|@$O|2H|P|2I|Q|R]]|9|@]|A|$]]|$1|W|3|-4|5|6|7|2J|8|@]|9|@]|A|$]]|$1|X|3|Y|5|Z|7|2K|8|@$O|2L|P|2M|Q|R]|$O|2N|P|2O|Q|R]]|9|@]|A|$]]|$1|10|3|-4|5|6|7|2P|8|@]|9|@]|A|$]]|$1|11|3|-4|5|6|7|2Q|8|@]|9|@]|A|$]]|$1|12|3|13|5|6|7|2R|8|@]|9|@]|A|$]]|$1|14|3|-4|5|6|7|2S|8|@]|9|@]|A|$]]|$1|15|3|16|5|17|7|2T|8|@]|9|@$O|2U|P|2V|1|2W]]|A|$]]|$1|18|3|19|5|17|7|2X|8|@]|9|@$O|2Y|P|2Z|1|30]]|A|$]]|$1|1A|3|-4|5|6|7|31|8|@]|9|@]|A|$]]|$1|1B|3|1C|5|6|7|32|8|@$O|33|P|34|Q|R]|$O|35|P|36|Q|R]|$O|37|P|38|Q|R]|$O|39|P|3A|Q|R]]|9|@]|A|$]]|$1|1D|3|1E|5|6|7|3B|8|@]|9|@]|A|$]]|$1|1F|3|1G|5|F|7|3C|8|@]|9|@]|A|$G|H]]|$1|1H|3|1I|5|6|7|3D|8|@]|9|@]|A|$]]|$1|1J|3|1K|5|6|7|3E|8|@$O|3F|P|3G|Q|R]]|9|@]|A|$]]|$1|1L|3|1M|5|6|7|3H|8|@$O|3I|P|3J|Q|R]]|9|@]|A|$]]|$1|1N|3|1O|5|6|7|3K|8|@$O|3L|P|3M|Q|R]]|9|@]|A|$]]|$1|1P|3|1Q|5|6|7|3N|8|@]|9|@]|A|$]]|$1|1R|3|1S|5|6|7|3O|8|@$O|3P|P|3Q|Q|R]|$O|3R|P|3S|Q|R]|$O|3T|P|3U|Q|R]]|9|@]|A|$]]|$1|1T|3|1U|5|6|7|3V|8|@]|9|@]|A|$]]|$1|1V|3|-4|5|6|7|3W|8|@]|9|@]|A|$]]]|1W|$1X|$5|1Y|1Z|20|A|$21|16]]|22|$5|1Y|1Z|20|A|$21|19]]]]

Here's a way I am doing it after researching it for a while. I wanted to make a Laravel API endpoint that checks if a field is "in use", so the important information is: 1) which DB table? 2) what DB column? and 3) is there a value in that column that matches the search terms?

Knowing this, we can construct our associative array:

<pre><code>$SEARCHABLE_TABLE_COLUMNS = [
 'users' =&gt; [ 'email' ],
];
</code></pre>

Then, we can set our values that we will check:

<pre><code>$table = 'users';
$column = 'email';
$value = 'alice@bob.com';
</code></pre>

Then, we can use <code>array_key_exists()</code> and <code>in_array()</code> with eachother to execute a one, two step combo and then act upon the <code>truthy</code> condition:

<pre><code>// step 1: check if 'users' exists as a key in `$SEARCHABLE_TABLE_COLUMNS`
if (array_key_exists($table, $SEARCHABLE_TABLE_COLUMNS)) {

 // step 2: check if 'email' is in the array: $SEARCHABLE_TABLE_COLUMNS[$table]
 if (in_array($column, $SEARCHABLE_TABLE_COLUMNS[$table])) {

 // if table and column are allowed, return Boolean if value already exists
 // this will either return the first matching record or null
 $exists = DB::table($table)-&gt;where($column, '=', $value)-&gt;first();

 if ($exists) return response()-&gt;json([ 'in_use' =&gt; true ], 200);
 return response()-&gt;json([ 'in_use' =&gt; false ], 200);
 }

 // if $column isn't in $SEARCHABLE_TABLE_COLUMNS[$table],
 // then we need to tell the user we can't proceed with their request
 return response()-&gt;json([ 'error' =&gt; 'Illegal column name: '.$column ], 400);
}

// if $table isn't a key in $SEARCHABLE_TABLE_COLUMNS,
// then we need to tell the user we can't proceed with their request
return response()-&gt;json([ 'error' =&gt; 'Illegal table name: '.$table ], 400);
</code></pre>

I apologize for the Laravel-specific PHP code, but I will leave it because I think you can read it as pseudo-code. The important part is the two <code>if</code> statements that are executed synchronously.

<blockquote>
 <code>array_key_exists()</code> and <code>in_array()</code> are PHP functions.
</blockquote>

source:

<ul>
<li><a href="https://php.net/manual/en/function.array-key-exists.php" rel="nofollow noreferrer">https://php.net/manual/en/function.array-key-exists.php</a></li>
<li><a href="https://php.net/manual/en/function.in-array.php" rel="nofollow noreferrer">https://php.net/manual/en/function.in-array.php</a></li>
</ul>

The nice thing about the algorithm that I showed above is that you can make a REST endpoint such as <code>GET /in-use/{table}/{column}/{value}</code> (where <code>table</code>, <code>column</code>, and <code>value</code> are variables).

You could have:

<pre><code>$SEARCHABLE_TABLE_COLUMNS = [
 'accounts' =&gt; [ 'account_name', 'phone', 'business_email' ],
 'users' =&gt; [ 'email' ],
];
</code></pre>

and then you could make GET requests such as:

<code>GET /in-use/accounts/account_name/Bob's Drywall</code> (you may need to uri encode the last part, but usually not)

<code>GET /in-use/accounts/phone/888-555-1337</code>

<code>GET /in-use/users/email/alice@bob.com</code>

Notice also that no one can do:

<code>GET /in-use/users/password/dogmeat1337</code> because <code>password</code> is not listed in your list of allowed columns for <code>user</code>.

Good luck on your journey.

I have two arrays in PHP as follows:

People:

<pre><code>Array
(
 [0] =&gt; 3
 [1] =&gt; 20
)
</code></pre>

Wanted Criminals:

<pre><code>Array
(
 [0] =&gt; 2
 [1] =&gt; 4
 [2] =&gt; 8
 [3] =&gt; 11
 [4] =&gt; 12
 [5] =&gt; 13
 [6] =&gt; 14
 [7] =&gt; 15
 [8] =&gt; 16
 [9] =&gt; 17
 [10] =&gt; 18
 [11] =&gt; 19
 [12] =&gt; 20
)
</code></pre>

How do I check if any of the People elements are in the Wanted Criminals array?

In this example, it should return <code>true</code> because <code>20</code> is in Wanted Criminals.

Checking to see if one array's elements are in another array in PHP

性能测试

我在PHP中有两个数组，如下所示：人物：Array(    [0] => 3    [1] => 20)通缉犯：Array(    [0] => 2    [1] => 4    [2] => 8    [3] => 11    [4] => 12    [5] => 13    [6] => 14    [7] => 15    [8] => 16    [9] => 17    [10] =>

问在PHP中检查一个数组的元素是否在另一个数组中
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