blocks|key|1094485|text|因为相等运算符==强制或转换数据类型，以查看它是否等于另一个操作数，而===+(标识运算符)不需要做任何转换，因此完成的工作更少，这使得它更快。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1094486|entityMap^0|7|2|Z|3|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

Because the equality operator <code>==</code> coerces, or converts, the data type temporarily to see if it’s equal to the other operand, whereas <code>===</code> (the identity operator) doesn’t need to do any converting whatsoever and thus less work is done, which makes it faster.

blocks|key|1094583|text|===不执行类型转换，因此0+==+'0'的计算结果为true，而0+===+'0'+-为false。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1094584|entityMap^0|0|3|D|8|R|4|X|9|19|5|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]|$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|G|$]]

<code>===</code> does not perform typecasting, so <code>0 == '0'</code> evaluates to <code>true</code>, but <code>0 === '0'</code> - to <code>false</code>.

blocks|key|1094526|text|我真的不知道它是否快很多，但在大多数语言中，===是直接的类型比较，而==会在必要/可能的情况下尝试进行类型强制以获得匹配。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1094527|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I don't really know if it's significantly faster, but === in most languages is a direct type comparison, while == will try to do type coercion if necessary/possible to gain a match.

blocks|key|1309781|text|因为在比较它们之前===+doesn't+need+to+coerce+the+operands+to+be+of+the+same+type。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1309782|不过，我怀疑速度上的差异是不是很大。在正常情况下，您应该使用更有意义的运算符。|1309783|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/80646/how-do-the-equality-and-identity-comparison-operators-differ^0|9|3|D|1M|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@$9|S|A|T|1|U]]|E|$]]|$1|F|3|G|5|6|7|V|8|@]|D|@]|E|$]]|$1|H|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]]]

Because <code>===</code> <a href="https://stackoverflow.com/questions/80646/how-do-the-equality-and-identity-comparison-operators-differ">doesn't need to coerce the operands to be of the same type</a> before comparing them.

I doubt the difference in speed is very much though. Under normal circumstances you should use whichever operator makes more sense.

blocks|key|1094629|text|在比较之前，==会产生较大的类型转换开销。===首先检查类型，然后在不进行任何类型转换的情况下继续。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1094630|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

The == incurs a larger overhead of type conversion before comparison. === first checks the type, then proceeds without having to do any type conversion.

blocks|key|1094699|text|总而言之，===更快，因为不转换数据类型来查看两个变量是否具有相同的值，但当您需要查看两个变量是否具有相同的值时，如果不知道变量的类型是什么，则使用==，或者如果变量的类型也很重要，则使用===。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1094700|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

In conclusion === is faster because don't converts the data type to see if two variables have same value, but when you need to see if two variables have same value you will use == if doesen't mather what type are variables, or === if is important also the type of variables.

blocks|key|1310052|text|在php+(c代码)中，value是一个“类”，类似于：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1310053|class+value
{
++++$int_;
++++$float_;
++++$string_;
++++$array_;
++++$object_;
}|code-block|syntax|javascript|1310054|当你比较$a+==+$b和$a是int类型时，会有类似的结果：|offset|length|style|CODE|1310055|if+($a->int_+==+$b->int_+%7C%7C+$a->int_+==+(int)+$b->float_+%7C%7C+$a->int_+==+(int)+$b->string_+%7C%7C+...)|1310056|但是string+'1'不会被转换为ascii代码49，它将是1。|1310057|当你比较$a+===+$b和$a是int类型时，会出现这样的情况：|1310058|if+($a->int_+==+$b->int_)|1310059|entityMap^0|0|0|4|8|D|2|G|3|0|0|2|6|9|3|P|2|V|1|0|4|9|E|2|H|3|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@$I|Z|J|10|K|L]|$I|11|J|12|K|L]|$I|13|J|14|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|15|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|16|8|@$I|17|J|18|K|L]|$I|19|J|1A|K|L]|$I|1B|J|1C|K|L]|$I|1D|J|1E|K|L]]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1F|8|@$I|1G|J|1H|K|L]|$I|1I|J|1J|K|L]|$I|1K|J|1L|K|L]]|9|@]|A|$]]|$1|S|3|T|5|D|7|1M|8|@]|9|@]|A|$E|F]]|$1|U|3|-4|5|6|7|1N|8|@]|9|@]|A|$]]]|V|$]]

In php (c code) value is a "class" like:

<pre><code>class value
{
 $int_;
 $float_;
 $string_;
 $array_;
 $object_;
}
</code></pre>

When your are comparing <code>$a == $b</code> and <code>$a</code> is <code>int</code> type, there will be something like:

<pre><code>if ($a-&gt;int_ == $b-&gt;int_ || $a-&gt;int_ == (int) $b-&gt;float_ || $a-&gt;int_ == (int) $b-&gt;string_ || ...)
</code></pre>

but <code>string</code> <code>'1'</code> will not be cast to ascii code <code>49</code>, it will be <code>1</code>.

When you are comparing <code>$a === $b</code> and <code>$a</code> is <code>int</code> type, there will be someting like:

<pre><code>if ($a-&gt;int_ == $b-&gt;int_)
</code></pre>

blocks|key|1310083|text|我发现这两个运算符之间实际上存在显著的速度差异。在下面的docker容器中运行php+8.0.0+RC5和php+7.4.12的结果。该项目托管在github上，因此每个人都可以审查该方法。免责声明:我构建了这个工具。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1310084|$+php+src/benchmark.php+--custom+--filter+~equal~
PHP+benchmark

-------------------------------
platform+++++++++++:++Linux+x64
php+version++++++++:+++++7.4.12
xdebug+++++++++++++:++++++++off
memory+limit+++++++:+++++++128M
max+execution++++++:++++++++++0
time+per+iteration+:+++++++50ms
iterations+++++++++:++++++++100
-------------------------------
---------------------------------------------------
0++++++++++++++++++:+++++++++==+++++++===
mean+++++++++++++++:+++++394156++++459015++++%2B16.5%25
median+++++++++++++:+++++397448++++461822++++%2B16.2%25
mode+++++++++++++++:+++++398154++++458062++++%2B15.0%25
minimum++++++++++++:+++++313271++++405692++++%2B29.5%25
maximum++++++++++++:+++++411157++++480360++++%2B16.8%25
quartile+1+++++++++:+++++393222++++454952++++%2B15.7%25
quartile+3+++++++++:+++++400881++++466491++++%2B16.4%25
IQ+range+++++++++++:+++++++7659+++++11538++++%2B50.7%25
std+deviation++++++:++++++15593+++++11867++++-23.9%25
normality++++++++++:+++++++0.8%25++++++0.8%25
---------------------------------------------------

$+php+src/benchmark.php+--custom+--filter+~equal~
PHP+benchmark

-------------------------------
platform+++++++++++:++Linux+x64
php+version++++++++:+++8.0.0RC5
xdebug+++++++++++++:++++++++off
memory+limit+++++++:+++++++128M
max+execution++++++:++++++++++0
time+per+iteration+:+++++++50ms
iterations+++++++++:++++++++100
-------------------------------
---------------------------------------------------
0++++++++++++++++++:+++++++++==+++++++===
mean+++++++++++++++:+++++405032++++474768++++%2B17.2%25
median+++++++++++++:+++++409226++++477313++++%2B16.6%25
mode+++++++++++++++:+++++408421++++479741++++%2B17.5%25
minimum++++++++++++:+++++311606++++386509++++%2B24.0%25
maximum++++++++++++:+++++417895++++491842++++%2B17.7%25
quartile+1+++++++++:+++++405740++++473436++++%2B16.7%25
quartile+3+++++++++:+++++412677++++483139++++%2B17.1%25
IQ+range+++++++++++:+++++++6937++++++9703++++%2B39.9%25
std+deviation++++++:++++++17501+++++15657++++-10.5%25
normality++++++++++:+++++++1.0%25++++++1.0%25
---------------------------------------------------|code-block|syntax|javascript|1310085|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/8ctopus/php-benchmark^0|21|6|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

I found out that there actually is a significant speed difference between the 2 operators. Results for php 8.0.0 RC5 and php 7.4.12 running in docker container below. The project is hosted on <a href="https://github.com/8ctopus/php-benchmark" rel="nofollow noreferrer">github</a> so everyone can review the methodology. Disclaimer: I built the tool.
<pre class="lang-sh prettyprint-override"><code>$ php src/benchmark.php --custom --filter ~equal~
PHP benchmark

-------------------------------
platform : Linux x64
php version : 7.4.12
xdebug : off
memory limit : 128M
max execution : 0
time per iteration : 50ms
iterations : 100
-------------------------------
---------------------------------------------------
0 : == ===
mean : 394156 459015 +16.5%
median : 397448 461822 +16.2%
mode : 398154 458062 +15.0%
minimum : 313271 405692 +29.5%
maximum : 411157 480360 +16.8%
quartile 1 : 393222 454952 +15.7%
quartile 3 : 400881 466491 +16.4%
IQ range : 7659 11538 +50.7%
std deviation : 15593 11867 -23.9%
normality : 0.8% 0.8%
---------------------------------------------------

$ php src/benchmark.php --custom --filter ~equal~
PHP benchmark

-------------------------------
platform : Linux x64
php version : 8.0.0RC5
xdebug : off
memory limit : 128M
max execution : 0
time per iteration : 50ms
iterations : 100
-------------------------------
---------------------------------------------------
0 : == ===
mean : 405032 474768 +17.2%
median : 409226 477313 +16.6%
mode : 408421 479741 +17.5%
minimum : 311606 386509 +24.0%
maximum : 417895 491842 +17.7%
quartile 1 : 405740 473436 +16.7%
quartile 3 : 412677 483139 +17.1%
IQ range : 6937 9703 +39.9%
std deviation : 17501 15657 -10.5%
normality : 1.0% 1.0%
---------------------------------------------------
</code></pre>

blocks|key|1310005|text|如果测试结果是正确的，那么一定是编译器问题，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1310006|处理器会在一个时钟周期内做任何让它做的事情|1310007|如果它要做的事情少了，那么它就会做得更快|1310008|添加：|1310009|实际上，如果编译器已经创建了大量要处理的机器代码，那么如果它已经添加了无数的东西来处理需要比较的数据类型，那么删除一个“次要”if将不会有太大的速度变化。|1310010|如果有人还在读这篇文章，那么我会对更多的讨论感兴趣。|1310011|菲尔|1310012|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Q|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|R|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|S|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|T|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|U|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|V|8|@]|9|@]|A|$]]|$1|N|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|O|$]]

If the test results are correct, then it must be a compiler issue,

The processor will do whatever it is told to do on a clock cycle

If it has less to do then it will be quicker to do

Addition:

Ah well actually if the compiler has already created loads of machine code to be processed, then if it has already added zillions of stuff to cope with what type of data needs comparing, then the removal of one "minor" IF will not change speeds much at all. 

If anyone still reads this are then I am interesting in more discussion.

Phil

Why is <code>===</code> faster than <code>==</code> in PHP?

问为什么在PHP中===比==快？
EN

回答 9

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问为什么在PHP中===比==快？EN

回答 9

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问为什么在PHP中===比==快？
EN