blocks|key|1113321|text|在本例中，我所做的是传递一个数组，其中键是参数名，值是值。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1113322|$optional+=+array(
++"param"+=>+$param1,
++"param2"+=>+$param2
);

function+func($required,+$requiredTwo,+$optional)+{
++if(isset($optional["param2"]))+{
++++doWork();
++}
}|code-block|syntax|javascript|1113323|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

What I have done in this case is pass an array, where the key is the parameter name, and the value is the value. 

<pre><code>$optional = array(
 "param" =&gt; $param1,
 "param2" =&gt; $param2
);

function func($required, $requiredTwo, $optional) {
 if(isset($optional["param2"])) {
 doWork();
 }
}
</code></pre>

blocks|key|1113333|text|func(+"1",+"2",+default,+default,+default,+default,+default,+"eight"+);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1113334|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>func( "1", "2", default, default, default, default, default, "eight" );
</code></pre>

blocks|key|1113383|text|如果您通常只是传入第8个值，则可以重新排序参数，使其成为第一个值。您只需要指定参数，直到您想要设置的最后一个参数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1113384|如果使用不同的值，则有两个选项。|1113385|一种方法是创建一组包装器函数，这些函数接受不同的参数，并在其他函数上设置默认值。如果您只使用几个组合，这是很有用的，但很快就会变得非常混乱。|1113386|另一种选择是传递一个数组，其中键是参数的名称。然后，您可以只检查数组中是否有带键的值，如果没有，则使用默认值。但同样，如果您有很多参数，这可能会变得混乱，并添加大量额外的代码。|1113387|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

If you are commonly just passing in the 8th value, you can reorder your parameters so it is first. You only need to specify parameters up until the last one you want to set.

If you are using different values, you have 2 options.

One would be to create a set of wrapper functions that take different parameters and set the defaults on the others. This is useful if you only use a few combinations, but can get very messy quickly.

The other option is to pass an array where the keys are the names of the parameters. You can then just check if there is a value in the array with a key, and if not use the default. But again, this can get messy and add a lot of extra code if you have a lot of parameters.

blocks|key|1113446|text|要实现您想要的功能，可以使用数组Like+Rabbot+said+(不过，如果过度使用，这可能会成为文档记录/维护的一项痛苦)。或者只使用传统的可选参数。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1113447|//My+function+with+tons+of+optional+params
function+my_func($req_a,+$req_b,+$opt_a+=+NULL,+$opt_b+=+NULL,+$opt_c+=+NULL)
{
++//Do+stuff
}
my_func('Hi',+'World',+null,+null,+'Red');|code-block|syntax|javascript|1113448|然而，我通常会发现，当我开始编写一个带有那么多参数的函数/方法时--通常情况下，它是一种代码气味，可以被重构/抽象成更干净的东西。|1113449|//Specialization+of+my_func+-+assuming+my_func+itself+cannot+be+refactored
function+my_color_func($reg_a,+$reg_b,+$opt+=+'Red')
{
++return+my_func($reg_a,+$reg_b,+null,+null,+$opt);
}
my_color_func('Hi',+'World');
my_color_func('Hello',+'Universe',+'Green');|1113450|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/3978929/php-function-with-optional-parameters/3978975#3978975^0|G|G|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|C|$]]|$1|K|3|L|5|F|7|10|8|@]|9|@]|C|$G|H]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

To accomplish what you want, use an array <a href="https://stackoverflow.com/questions/3978929/php-function-with-optional-parameters/3978975#3978975">Like Rabbot said</a> (though this can become a pain to document/maintain if used excessively). Or just use the traditional optional args.

<pre><code>//My function with tons of optional params
function my_func($req_a, $req_b, $opt_a = NULL, $opt_b = NULL, $opt_c = NULL)
{
 //Do stuff
}
my_func('Hi', 'World', null, null, 'Red');
</code></pre>

However, I usually find that when I start writing a function/method with that many arguments - more often than not it is a code smell, and can be re-factored/abstracted into something much cleaner.

<pre><code>//Specialization of my_func - assuming my_func itself cannot be refactored
function my_color_func($reg_a, $reg_b, $opt = 'Red')
{
 return my_func($reg_a, $reg_b, null, null, $opt);
}
my_color_func('Hi', 'World');
my_color_func('Hello', 'Universe', 'Green');
</code></pre>

blocks|key|1113495|text|我知道这是一个古老的帖子，但我遇到了像OP这样的问题，这就是我想出来的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1113496|可以传递的数组示例。如果需要特定的顺序，您可以重新排序，但对于这个问题，这将执行所要求的操作。|1113497|$argument_set+=+array+(8+=>+'lots',+5+=>+'of',+1+=>+'data',+2+=>+'here');|code-block|syntax|javascript|1113498|这是易于管理的，易于阅读的，数据提取点可以在代码中的任何地方随时添加和删除，并且仍然可以避免大规模的重写。我使用了整数键来符合OP的原始问题，但字符串键也可以很容易地使用。事实上，为了可读性，我建议这样做。|1113499|为方便起见，请将此文件保存在外部文件中|1113500|function+unknown_number_arguments($argument_set)+{

++++foreach+($argument_set+as+$key+=>+$value)+{

++++++++#+create+a+switch+with+all+the+cases+you+need.+as+you+loop+the+array+
++++++++#+keys+only+your+submitted+$keys+values+will+be+found+with+the+switch.+
++++++++switch+($key)+{
++++++++++++case+1:
++++++++++++++++#+do+stuff+with+$value
++++++++++++++++break;
++++++++++++case+2:
++++++++++++++++#+do+stuff+with+$value;
++++++++++++++++break;
++++++++++++case+3:
++++++++++++++++#+key+3+omitted,+this+wont+execute+
++++++++++++++++break;
++++++++++++case+5:
++++++++++++++++#+do+stuff+with+$value;
++++++++++++++++break;
++++++++++++case+8:
++++++++++++++++#+do+stuff+with+$value;
++++++++++++++++break;
++++++++++++default:
++++++++++++++++#+no+match+from+the+array,+do+error+logging?
++++++++++++++++break;
++++++++}
++++}
return;
}|1113501|如果文件有问题，请把这个放在开头。|1113502|$argument_set+=+array();+|1113503|只需使用这些来分配下一段数据，并根据数据的来源进行编号/命名。|1113504|$argument_set[1][]+=+$some_variable;+|1113505|并最终传递数组|1113506|unknown_number_arguments($argument_set);|1113507|entityMap^0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|13|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|14|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|15|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|16|8|@]|9|@]|A|$]]|$1|M|3|N|5|F|7|17|8|@]|9|@]|A|$G|H]]|$1|O|3|P|5|6|7|18|8|@]|9|@]|A|$]]|$1|Q|3|R|5|F|7|19|8|@]|9|@]|A|$G|H]]|$1|S|3|T|5|6|7|1A|8|@]|9|@]|A|$]]|$1|U|3|V|5|F|7|1B|8|@]|9|@]|A|$G|H]]|$1|W|3|X|5|6|7|1C|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|F|7|1D|8|@]|9|@]|A|$G|H]]|$1|10|3|-4|5|6|7|1E|8|@]|9|@]|A|$]]]|11|$]]

I know this is an old post, but i was having a problem like the OP and this is what i came up with.

Example of array you could pass. You could re order this if a particular order was required, but for this question this will do what is asked.

<pre><code>$argument_set = array (8 =&gt; 'lots', 5 =&gt; 'of', 1 =&gt; 'data', 2 =&gt; 'here');
</code></pre>

This is manageable, easy to read and the data extraction points can be added and removed at a moments notice anywhere in coding and still avoid a massive rewrite. I used integer keys to tally with the OP original question but string keys could be used just as easily. In fact for readability I would advise it.

Stick this in an external file for ease

<pre><code>function unknown_number_arguments($argument_set) {

 foreach ($argument_set as $key =&gt; $value) {

 # create a switch with all the cases you need. as you loop the array 
 # keys only your submitted $keys values will be found with the switch. 
 switch ($key) {
 case 1:
 # do stuff with $value
 break;
 case 2:
 # do stuff with $value;
 break;
 case 3:
 # key 3 omitted, this wont execute 
 break;
 case 5:
 # do stuff with $value;
 break;
 case 8:
 # do stuff with $value;
 break;
 default:
 # no match from the array, do error logging?
 break;
 }
 }
return;
}
</code></pre>

put this at the start if the file.

<pre><code>$argument_set = array(); 
</code></pre>

Just use these to assign the next piece of data use numbering/naming according to where the data is coming from.

<pre><code>$argument_set[1][] = $some_variable; 
</code></pre>

And finally pass the array

<pre><code>unknown_number_arguments($argument_set);
</code></pre>

blocks|key|898872|text|我认为，您也可以使用对象作为参数传输。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|898873|$myParam+=+new+stdClass();
$myParam->optParam2+=+'something';
$myParam->optParam8+=+3;
theFunction($myParam);

function+theFunction($fparam){++++++
++return+"I+got+".$fparam->optParam8."+of+".$fparam->optParam2."+received!";
}|code-block|syntax|javascript|898874|当然，你必须在这个函数中设置"optParam8“和"optParam2”的默认值，在其他情况下，你会得到“通知:未定义的属性:+stdClass::$optParam2”|898875|如果使用数组作为函数参数，我喜欢用这种方式设置默认值：|898876|function+theFunction($fparam){
+++$default+=+array(
++++++'opt1'+=>+'nothing',
++++++'opt2'+=>+1
+++);
+++if(is_array($fparam)){
++++++$fparam+=+array_merge($default,+$fparam);
+++}else{
++++++$fparam+=+$default;
+++}
+++//now,+the+default+values+are+overwritten+by+these+passed+by+$fparam
+++return+"I+received+".$fparam['opt1']."+and+".$fparam['opt2']."!";
}|898877|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]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|S|8|@]|9|@]|A|$E|F]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

I think, you can use objects as params-transportes, too.

<pre><code>$myParam = new stdClass();
$myParam-&gt;optParam2 = 'something';
$myParam-&gt;optParam8 = 3;
theFunction($myParam);

function theFunction($fparam){ 
 return "I got ".$fparam-&gt;optParam8." of ".$fparam-&gt;optParam2." received!";
}
</code></pre>

Of course, you have to set default values for "optParam8" and "optParam2" in this function, in other case you will get "Notice: Undefined property: stdClass::$optParam2"

If using arrays as function parameters, I like this way to set default values:

<pre><code>function theFunction($fparam){
 $default = array(
 'opt1' =&gt; 'nothing',
 'opt2' =&gt; 1
 );
 if(is_array($fparam)){
 $fparam = array_merge($default, $fparam);
 }else{
 $fparam = $default;
 }
 //now, the default values are overwritten by these passed by $fparam
 return "I received ".$fparam['opt1']." and ".$fparam['opt2']."!";
}
</code></pre>

blocks|key|898928|text|在PHP5.6和更高版本中，参数列表可能包括...标记来指示函数接受可变数量的参数。参数将作为数组传递给给定的变量；例如：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|898929|示例使用...访问变量参数|898930|<?php
function+sum(...$numbers)+{
++++$acc+=+0;
++++foreach+($numbers+as+$n)+{
++++++++$acc+%2B=+$n;
++++}
++++return+$acc;
}

echo+sum(1,+2,+3,+4);
?>|code-block|syntax|javascript|898931|上面的示例将输出：|898932|10|898933|Variable-length+argument+lists+PHP+Documentation|offset|length|898934|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/manual/en/functions.arguments.php#functions.variable-arg-list.new^0|0|0|0|0|0|0|1C|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|10|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|11|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|12|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|13|8|@]|9|@$O|14|P|15|1|16]]|A|$]]|$1|Q|3|-4|5|6|7|17|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]]]

In PHP 5.6 and later, argument lists may include the ... token to denote that the function accepts a variable number of arguments. The arguments will be passed into the given variable as an array; for example:

Example Using ... to access variable arguments

<pre><code>&lt;?php
function sum(...$numbers) {
 $acc = 0;
 foreach ($numbers as $n) {
 $acc += $n;
 }
 return $acc;
}

echo sum(1, 2, 3, 4);
?&gt;
</code></pre>

The above example will output:

<pre><code>10
</code></pre>

<a href="http://php.net/manual/en/functions.arguments.php#functions.variable-arg-list.new" rel="noreferrer">Variable-length argument lists PHP Documentation</a>

blocks|key|1113699|text|您可以将缺省值设置为null。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1113700|<?php
function+functionName($value,+$value2+=+null)+{
//+do+stuff
}|code-block|syntax|javascript|1113701|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can just set the default value to null.

<pre><code>&lt;?php
function functionName($value, $value2 = null) {
// do stuff
}
</code></pre>

blocks|key|899039|text|function+yourFunction($var1,+$var2,+$optional+=+Null){
+++...+code
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|899040|您可以创建一个常规函数，然后通过为可选变量指定一个默认的空值来添加它们。|unstyled|899041|Null仍然是一个值，如果你不使用该变量的值调用函数，它就不会为空，所以不会出现错误。|899042|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|F|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>function yourFunction($var1, $var2, $optional = Null){
 ... code
}
</code></pre>

You can make a regular function and then add your optional variables by giving them a default Null value.

A Null is still a value, if you don't call the function with a value for that variable, it won't be empty so no error.

blocks|key|899114|text|PHP允许默认参数(link)。在本例中，您可以将3到8之间的所有参数定义为NULL或空字符串"“，具体取决于您的函数代码。这样，您只能使用前两个参数调用函数。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|899115|例如：|899116|<?php
++function+yourFunction($arg1,+$arg2,+$arg3=NULL,+$arg4=NULL,+$arg5=NULL,+$arg6=NULL,+$arg7=NULL,+$arg8=NULL){
echo+$arg1;
echo+$arg2;
if(isset($arg3)){echo+$arg3;}
#+other+similar+statements+for+$arg4,+....,+$arg5
if(isset($arg8)){echo+$arg8;}
}|code-block|syntax|javascript|899117|entityMap|0|LINK|mutability|MUTABLE|url|https://www.php.net/manual/en/functions.arguments.php^0|A|4|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|C|$I|J]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

PHP allows default arguments (<a href="https://www.php.net/manual/en/functions.arguments.php" rel="nofollow noreferrer">link</a>). In your case, you could define all the parameters from 3 to 8 as NULL or as an empty string "" depending on your function code. In this way, you can call the function only using the first two parameters.

For example:

<pre><code>&lt;?php
 function yourFunction($arg1, $arg2, $arg3=NULL, $arg4=NULL, $arg5=NULL, $arg6=NULL, $arg7=NULL, $arg8=NULL){
echo $arg1;
echo $arg2;
if(isset($arg3)){echo $arg3;}
# other similar statements for $arg4, ...., $arg5
if(isset($arg8)){echo $arg8;}
}
</code></pre>

blocks|key|899205|text|只需将Null设置为忽略不想使用的参数，然后根据位置设置所需的参数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|899206|+function+myFunc($p1,$p2,$p3=Null,$p4=Null,$p5=Null,$p6=Null,$p7=Null,$p8=Null){
++++for+($i=1;+$i<9;+$i%2B%2B){
++++++++$varName+=+"p$i";
++++++++if+(isset($$varName)){
++++++++++++echo+$varName."+=+".$$varName." \n";
++++++++}
++++}
}+++

myFunc(+"1",+"2",+Null,+Null,+Null,+Null,+Null,+"eight"+);|code-block|syntax|javascript|899207|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Just set Null to ignore parameters that you don't want to use and then set the parameter needed according to the position.
<pre><code> function myFunc($p1,$p2,$p3=Null,$p4=Null,$p5=Null,$p6=Null,$p7=Null,$p8=Null){
 for ($i=1; $i&lt;9; $i++){
 $varName = &quot;p$i&quot;;
 if (isset($$varName)){
 echo $varName.&quot; = &quot;.$$varName.&quot;&lt;br&gt;\n&quot;;
 }
 }
} 

myFunc( &quot;1&quot;, &quot;2&quot;, Null, Null, Null, Null, Null, &quot;eight&quot; );
</code></pre>

I've written a PHP function that can accept 10 parameters, but only 2 are required. Sometimes, I want to define the eighth parameter, but I don't want to type in empty strings for each of the parameters until I reach the eighth.
One idea I had was to pass an abstracted function with an array of parameters which passes it along to the real function.
Is there a better way to set up the function so I can pass in only the parameters I want?

PHP Function with Optional Parameters

我已经写了一个PHP函数，可以接受10个参数，但只需要2个参数。有时，我想定义第八个参数，但在到达第八个参数之前，我不想为每个参数键入空字符串。我的一个想法是传递一个带有参数数组的抽象函数，该数组将其传递给实际函数。有没有更好的方法来设置函数，这样我就可以只传递我想要的参数了？

问带可选参数的PHP函数
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