php 如何检查数组值是否存在？

How to check if an array value exists?

提问by Uffo

How can I check if $something['say']has the value of 'bla'or 'omg'?

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

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

回答by Benjamin Ortuzar

You could use the PHP in_arrayfunction

您可以使用 PHP in_array函数

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

回答by Tatu Ulmanen

Using if?

使用if?

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

Btw, you are assigning an value with the key saytwice, hence your array will result in an array with only one value.

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

回答by Neeraj Singh

Using:in_array()

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";
}

Here is output:The 'prize_id' element is in the array

这是输出：The 'prize_id' element is in the array

---

---

Using:array_key_exists()

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";
}

No output

无输出

---

---

In conclusion, array_key_exists()does not work with a simple array. Its only to find whether an array key exist or not. Use in_array()instead.

总之，array_key_exists()不适用于简单的数组。它只是查找数组键是否存在。使用in_array()来代替。

Here is more example:

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 ||
 */
?>

Here is PHP DEMO

这是 PHP DEMO

回答by Jasir

You can use:

您可以使用：

• array_search()
• in_array()
• a combination of array_flip()and array_key_exists()

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

回答by echo

To check if the index is defined: isset($something['say'])

要检查索引是否已定义： isset($something['say'])

回答by Tom Jowitt

in_array() is fine if you're only checking but if you need to check that a value exists and return the associated key, array_search is a better option.

in_array() 如果您只是检查就可以，但如果您需要检查值是否存在并返回关联的键，则 array_search 是更好的选择。

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

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

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

This will print "Key is 1"

这将打印“Key is 1”

回答by VolkerK

You can test whether an array has a certain element at all or not with isset()or sometimes even better array_key_exists()(the documentation explains the differences). If you can't be sure if the array has an element with the index 'say' you should test that first or you might get 'warning: undefined index....' messages.

您可以使用isset()或有时甚至更好的array_key_exists()测试数组是否具有某个元素（文档解释了差异）。如果您不能确定数组是否有一个索引为“say”的元素，您应该首先测试它，否则您可能会收到“警告：未定义索引....”消息。

As for the test whether the element's value is equal to a string you can use == or (again sometimes better) the identity operator ===which doesn't allow type juggling.

至于测试元素的值是否等于字符串，您可以使用 == 或（有时更好）身份运算符===不允许类型杂耍。

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

回答by Vishnu Sharma

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

回答by Xman Classical

Just use the PHP function array_key_exists()

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";
}
?>

回答by animuson

Well, first off an associative array can only have a key defined once, so this array would never exist. Otherwise, just use in_array()to determine if that specific array element is in an array of possible solutions.

好吧，首先关联数组只能定义一次键，所以这个数组永远不会存在。否则，仅用于in_array()确定该特定数组元素是否在可能解决方案的数组中。