php is in the array

In the process of PHP development, array-related operations are often involved, including array search, addition, modification, deletion, etc. Among them, determining whether an element exists in an array is one of the common operations. In PHP, there are several ways to determine whether an element is in an array.

1. Use the in_array() function

The in_array() function can determine whether the specified element exists in the array. The syntax is as follows:

in_array($needle, $haystack, $strict)

Among them, $needle represents the element to be found, $haystack represents the array to be found, and $strict represents whether to enable it. Strict mode, if enabled, requires the elements to be of the same type as the elements in the array, and the values ​​to be the same.

The following are some examples:

1. Determine whether the number exists in the array

$nums = array(1, 2, 3, 4, 5);
if (in_array(3, $nums)) {

echo "存在";

} else {

echo "不存在";

}

The output result is: existence

2. Judgment Whether the string exists in the array

$fruits = array("apple", "banana", "orange");
if (in_array("banana", $fruits)) {

echo "存在";

} else {

echo "不存在";

}

The output result is: Existence

3. Determine whether the types of elements are the same

$a = 1 ;
$b = "1";
$arr ​​= array(1, "1");

if (in_array($a, $arr, true)) {

echo "存在";

} else {

echo "不存在";

}

if (in_array($b, $arr, true)) {

echo "存在";

} else {

echo "不存在";

}

The output result is: exists or not

2. Use array_search() function

array_search() function can find the position of the specified element in the array. If found , returns the index of the element in the array, otherwise returns false. The syntax is as follows:

array_search($needle, $haystack, $strict)

Among them, $needle represents the element to be searched, $haystack represents the array to be searched, and $strict represents whether to enable it. Strict mode.

The following are some examples:

1. Find the position of the number in the array

$nums = array(1, 2, 3, 4, 5);
$key = array_search(3, $nums);

if ($key !== false) {

echo "该元素在数组中的位置为：" . $key;

} else {

echo "不存在";

}

The output result is: the position of the element in the array is: 2

2. Find the position of the string in the array

$fruits = array("apple", "banana" , "orange");
$key = array_search("banana", $fruits);

if ($key !== false) {

echo "该元素在数组中的位置为：" . $key;

} else {

echo "不存在";

}

The output result is: the position of the element in the array is: 1

3. Use isset() function

isset() function can Used to determine whether the specified key exists in the array. The syntax is as follows:

isset($array[$key])

Among them, $array represents the array to be judged, and $key represents the key to be judged.

The following is an example:

$fruits = array("apple" => 1, "banana" => 2, "orange" => 3);

if (isset($fruits["banana"])) {

echo "存在";

} else {

echo "不存在";

}

The output result is: exists

4. Use array_key_exists() function

array_key_exists() function can determine whether the specified key exists in the array. The syntax is as follows:

array_key_exists($key, $array)

Among them, $key represents the key to be judged, and $array represents the array to be judged.

The following is an example:

$fruits = array("apple" => 1, "banana" => 2, "orange" => 3);

if (array_key_exists("banana", $fruits)) {

echo "存在";

} else {

echo "不存在";

}

The output result is: exists

In summary, PHP provides multiple ways to determine whether an element exists in an array. In actual development, the most appropriate method can be selected according to the specific situation.

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