PHP：如何使用类键从数组中获取元素

如果我有这样的数组

array [
       y => 35
       x => 51
       z => 35
       c_3 => 4
       c_1 => 54
       c_6 => 53
       c_9 => 52
] 

我想得到一个数组

array [c_3=>4, c_1=>54, c_6=>53, c_9=>52]

如果没有不需要的字段，请使用array\u slice：如果需要，只需选择已知的键即可。这里提供了按键筛选数组的解决方案：

尝试以下方法：

$filtred = array();

foreach($yourArray as $key => $value)
  if(preg_match('/c_\d/',$key))
    $filtred[] = $value;

print_r($filtred);

---

您可以尝试使用

array\u filter（）

网上有一些有趣的例子。其中一个涉及筛选数组键。

试试这个

 //your array
    $arr1 = array (
           "y" => 35,
           "x" => 51,
           "z" => 35,
           "c_3" => 4,
           "c_1" => 54,
           "c_6" => 53,
           "c_9" => 52
    );
// Array with keys you want
    $arr2 =  array (
           "c_3" => '',
           "c_1" => '',
           "c_6" => '',
           "c_9" => ''
    );
//use array_intersect_key to find the common  ;)
    print_r(array_intersect_key($arr1,$arr2));

---

事实上，我也有类似的问题，并在这里寻找答案，但没有什么真正符合我的期望

我想要一些更可重用的东西，可以在我所有的项目中使用，所以我最终编写了这个函数：

    /**
* Create a new a array containing only the key with a certain $pattern or $subString.
*
* Note: You cannot use both $subString and $pattern at once ($substring has precedence on $pattern).
*
* @param $errorMessage String to return the error message.
* @param $source Array in which we must extract data.
* @param $subString String/Int/Array substring (or array of substring) to seek in the key name.
* @param $pattern String regex for validating the key.
* @param $useValueAsKey Boolean if true it will use the value as the key in the new array (scalar values only).
*/
public static function extractSubArray(&$errorMessage, array &$source, $subString ="", $pattern = "", $useValueAsKey=false){

    $newArray = array();

    $errorMessage = "";

    $dbManager = GeneralDbManager::getInstance();

    if (empty($source)){

        $errorMessage = $dbManager->getErrorMessage("SOURCE_ARRAY_IS_EMPTY_ERR", "The array supplied is empty.");
    }
    elseif(empty($subString) and empty($pattern)){

        $errorMessage = $dbManager->getErrorMessage("NO_SUBSTR_OR_PATTERN_ERR", "There are no substring or pattern to match the keys in the array.");
    }
    elseif (!empty($subString) and !(is_string($subString) or is_numeric($subString) or is_array($subString))){

        $errorMessage = $dbManager->getErrorMessage("INVALID_MATCH_SUBSTRING_ERR", "The substring you supplied to match the keys is invalid.");
    }
    elseif(!empty($pattern) and !RegularExpression::testRegex($pattern)){

        $errorMessage = $dbManager->getErrorMessage("INVALID_MATCH_PATTERN_ERR", "The regular expression you supplied to match the keys is invalid.");
    }
    else{

        foreach ($source as $key => $value){

            if (self::isKeyMatchSubstring($key, $subString, $pattern)){

                if ($useValueAsKey and (is_string($value) or is_numeric($value))){

                    $newArray[$value] = $value;     
                }
                else{

                    $newArray[$key] = $value;
                }
            }       
        }

        if (empty($newArray)){

            $errorMessage = $dbManager->getErrorMessage("INVALID_MATCH_PATTERN_ERR", "We were not able to match any keys in the array with the substring or the regular expression.");
        }
    }

    unset($dbManager);

    return $newArray;
}

/**
* Validate that the $key contains the $substring (string or array) or match the $pattern.
*
* @param $key String to validate
* @param $subString String/Int/Array containing the subString to seek.
* @param $pattern String regex for validating the key.
*/
private static function isKeyMatchSubstring($key, $subString, $pattern){

    $matched = false;

    if (!empty($subString)){

        if (is_string($subString) or is_numeric($subString)){

            if(strpos(strtolower($key), strtolower($subString)) !== false){

                $matched = true;    
            }
        }
        else{ //array

            foreach($subString as $testString){

                $matched = self::isKeyMatchSubstring($key, $testString, "");

                if ($matched){

                    break;  
                }
            }
        }   
    }
    elseif(!empty($pattern)){

        $matched = preg_match($pattern, $key);
    }

    return $matched;
}

它使用了一个名为testRegex（）的函数，因此我想我也可以提供该代码：

/**
* Make sure that a regular expression works in PHP.
*
* @param $regex String the regular expression to validate.
*
* @return Boolean
*/
public static function testRegex($regex){

    $isValid = false;

    if (!empty($regex) and is_string($regex)){

        if (@preg_match($regex, null) !== false){
            $isValid = true;
        }
    }

    return $isValid;
}

当然，没有单元测试的函数有多好

    public function testExtractSubArray(){

    $errorMessage = "";

    $source = array();

    //no data
    $this->assertEmpty(Tool::extractSubArray($errorMessage, $source, "", "", false));

    $this->assertNotEmpty($errorMessage);

    //no substring or pattern
    $source = array(1 => 1);


    $this->assertEmpty(Tool::extractSubArray($errorMessage, $source, "", "", false));

    $this->assertNotEmpty($errorMessage);


    //invalid substring
    $dbmanager = GeneralDbManager::getInstance();

    $this->assertEmpty(Tool::extractSubArray($errorMessage, $source, $dbmanager, "", false));

    $this->assertNotEmpty($errorMessage);

    unset($dbmanager);


    //invalid pattern
    $this->assertEmpty(Tool::extractSubArray($errorMessage, $source, "", "[]123", false));

    $this->assertNotEmpty($errorMessage);


    //no match
    $this->assertEmpty(Tool::extractSubArray($errorMessage, $source, "pokemon", "", false));

    $this->assertNotEmpty($errorMessage);


    //valid substring
    $source = array("woot1" => "homer", "woot2" => "bart", "woot3" => "lisa", "doh1" => "marge", "doh2" => "simpson");

    $newArray = Tool::extractSubArray($errorMessage, $source, "WOOT", "", false);


    $this->assertNotEmpty($newArray);

    $this->assertEmpty($errorMessage);

    $this->assertContains("homer", $newArray);

    $this->assertContains("bart", $newArray);

    $this->assertContains("lisa", $newArray);

    $this->assertNotContains("marge", $newArray);

    $this->assertNotContains("simpson", $newArray);


    //use value as key
    $newArray = Tool::extractSubArray($errorMessage, $source, "WOOT", "", true);


    $this->assertTrue(array_key_exists("homer", $newArray));

    $this->assertTrue(array_key_exists("bart", $newArray));

    $this->assertTrue(array_key_exists("lisa", $newArray));


    //substring array
    $source = array("stan_march" => "normal", "kyle_brofloski" => "jew", "eric_cartman" => "asshole", "kenny_mccormick" => "dead", "butters_stotch" => "pushover");

    $newArray = Tool::extractSubArray($errorMessage, $source, array("stan", "kyle", "cartman"), "", false);


    $this->assertNotEmpty($newArray);

    $this->assertEmpty($errorMessage);

    $this->assertContains("normal", $newArray);

    $this->assertContains("jew", $newArray);

    $this->assertContains("asshole", $newArray);

    $this->assertNotContains("dead", $newArray);

    $this->assertNotContains("pushover", $newArray);


    //regex
    $source = array("jonathan@woot.ca" => 1, "jonathan" => 2, "12345" => 3, "more $$$" => 4, "$?%$?%$%?" => 5);

    $newArray = Tool::extractSubArray($errorMessage, $source, "", RegularExpression::ALPHA_NUMERIC, false);


    $this->assertNotEmpty($newArray);

    $this->assertEmpty($errorMessage);

    $this->assertNotContains(1, $newArray);

    $this->assertContains(2, $newArray);

    $this->assertContains(3, $newArray);

    $this->assertNotContains(4, $newArray);

    $this->assertNotContains(5, $newArray);
}

附加说明：此代码使用getErrorMessage（）方法获取数据库中错误消息的翻译。由于这些错误消息用于调试目的，因此可以直接在代码中硬编码以提高性能（无需实例化类以获取错误消息并打开到数据库的连接）

嗯，我希望它能帮助像我这样的可重用性怪胎

---

来自蒙特利尔的Jonathan Parent-Lévesque

使用

阵列过滤器（）检查此解决方案

下面的解决方案将在PHP>=5.6.0中运行

 $filtered = array_filter($arr, function($k){
   return preg_match('#c_\d#', $k);
 }, ARRAY_FILTER_USE_KEY);

---

两种解决方案都有效，我已经检查过了

我曾尝试过上述解决方案，但在

PHP5.6中，上述解决方案均不适用于我

所以，我尝试并使用了不同的解决方案，这对我来说很有效

$subArray = array();

foreach($arryDetails as $key => $value)
  if(preg_match('/^c_/',$key))
    $subArray[$key] = $value;

print_r($subArray);

很好，我不知道那个命令。谁想知道更多关于数组的信息？关键字：好的现金解决方案。我认为数组过滤器（）是更好的解决方案。
$subArray = array();

foreach($arryDetails as $key => $value)
  if(preg_match('/^c_/',$key))
    $subArray[$key] = $value;

print_r($subArray);