如何检查数组值是否存在？

如何检查是否$something['say']具有'bla'或的值'omg'？

$something = array('say' => 'bla', 'say' => 'omg');

使用if？

if(isset($something['say']) && $something['say'] == 'bla') {
    // do something
}

顺便说一句，您将say两次用键分配一个值，因此您的数组将导致一个只有一个值的数组。

您可以使用PHP in_array函数

if( in_array( "bla" ,$yourarray ) )
{
    echo "has bla";
}

使用： in_array()

$search_array = array('user_from','lucky_draw_id','prize_id');

if (in_array('prize_id', $search_array)) {
    echo "The 'prize_id' element is in the array";
}

输出如下： The 'prize_id' element is in the array

使用： array_key_exists()

$search_array = array('user_from','lucky_draw_id','prize_id');

if (array_key_exists('prize_id', $search_array)) {
    echo "The 'prize_id' element is in the array";
}

无输出

总之，array_key_exists()不适用于简单数组。唯一的发现数组键是否存在。使用in_array()代替。

这是更多示例：

<?php
/**++++++++++++++++++++++++++++++++++++++++++++++
 * 1. example with assoc array using in_array
 *
 * IMPORTANT NOTE: in_array is case-sensitive
 * in_array — Checks if a value exists in an array
 *
 * DOES NOT WORK FOR MULTI-DIMENSIONAL ARRAY
 *++++++++++++++++++++++++++++++++++++++++++++++
 */
$something = array('a' => 'bla', 'b' => 'omg');
if (in_array('omg', $something)) {
    echo "|1| The 'omg' value found in the assoc array ||";
}

/**++++++++++++++++++++++++++++++++++++++++++++++
 * 2. example with index array using in_array
 *
 * IMPORTANT NOTE: in_array is case-sensitive
 * in_array — Checks if a value exists in an array
 *
 * DOES NOT WORK FOR MULTI-DIMENSIONAL ARRAY
 *++++++++++++++++++++++++++++++++++++++++++++++
 */
$something = array('bla', 'omg');
if (in_array('omg', $something)) {
    echo "|2| The 'omg' value found in the index array ||";
}

/**++++++++++++++++++++++++++++++++++++++++++++++
 * 3. trying with array_search
 *
 * array_search — Searches the array for a given value 
 * and returns the corresponding key if successful
 *
 * DOES NOT WORK FOR MULTI-DIMENSIONAL ARRAY
 *++++++++++++++++++++++++++++++++++++++++++++++
 */
$something = array('a' => 'bla', 'b' => 'omg');
if (array_search('bla', $something)) {
    echo "|3| The 'bla' value found in the assoc array ||";
}

/**++++++++++++++++++++++++++++++++++++++++++++++
 * 4. trying with isset (fastest ever)
 *
 * isset — Determine if a variable is set and 
 * is not NULL
 *++++++++++++++++++++++++++++++++++++++++++++++
 */
$something = array('a' => 'bla', 'b' => 'omg');
if($something['a']=='bla'){
    echo "|4| Yeah!! 'bla' found in array ||";
}

/**
 * OUTPUT:
 * |1| The 'omg' element value found in the assoc array ||
 * |2| The 'omg' element value found in the index array ||
 * |3| The 'bla' element value found in the assoc array ||
 * |4| Yeah!! 'bla' found in array ||
 */
?>

这是 PHP DEMO

您可以使用：

• array_search()
• in_array()
• 的组合array_flip()和array_key_exists()

要检查索引是否已定义： isset($something['say'])

您可以使用isset（）或有时甚至更好的array_key_exists（）来测试数组是否完全具有某个元素（文档解释了区别）。如果不确定数组是否具有索引为“ say”的元素，则应首先进行测试，否则可能会收到“警告：未定义的索引...”消息。

至于测试元素的值是否等于字符串，可以使用==，或者（有时更好）使用标识运算符===，它不允许类型变乱。

if( isset($something['say']) && 'bla'===$something['say'] ) {
  // ...
}

如果仅检查in_array（）很好，但是如果需要检查值是否存在并返回关联的键，则array_search是一个更好的选择。

$data = [
    'hello',
    'world'
];

$key = array_search('world', $data);

if ($key) {
    echo 'Key is ' . $key;
} else {
    echo 'Key not found';
}

这将打印“ Key is 1”

只需使用PHP函数 array_key_exists()

<?php
$search_array = array('first' => 1, 'second' => 4);
if (array_key_exists('first', $search_array)) {
    echo "The 'first' element is in the array";
}
?>

<?php
if (in_array('your_variable', $Your_array)) {
    $redImg = 'true code here';
} else {
    $redImg = 'false code here';
} 
?>

好吧，首先关联数组只能定义一次键，因此该数组将永远不存在。否则，仅用于in_array()确定该特定数组元素是否在可能的解决方案数组中。

bool in_array ( mixed $needle , array $haystack [, bool $strict = FALSE ] )

in_array in_array（）与数组作为指针的另一种用法

<?php
$a = array(array('p', 'h'), array('p', 'r'), 'o');

if (in_array(array('p', 'h'), $a)) {
    echo "'ph' was found\n";
}

if (in_array(array('f', 'i'), $a)) {
    echo "'fi' was found\n";
}

if (in_array('o', $a)) {
    echo "'o' was found\n";
}
?>

假设您使用的是简单数组

。即

$MyArray = array("red","blue","green");

您可以使用此功能

function val_in_arr($val,$arr){
  foreach($arr as $arr_val){
    if($arr_val == $val){
      return true;
    }
  }
  return false;
}

用法：

val_in_arr("red",$MyArray); //returns true
val_in_arr("brown",$MyArray); //returns false