How to determine if an element is in an array in php

In PHP programming, it is often necessary to determine whether an element is in an array. This is because array is an important data structure that can be used to store multiple elements and provides functions such as access, query, addition, and deletion. When we need to perform an operation, sometimes we need to check if an element is in an array.

In PHP, we can use the in_array() function to determine whether an element is in an array. This function accepts two parameters, the first parameter is the element to be found, and the second parameter is the array to be found. This function returns TRUE if the element exists in the array, otherwise it returns FALSE.

For example, the code is as follows:

$arr = array('apple', 'banana', 'orange');
if (in_array('apple', $arr)) {
    echo "apple exists in array";
} else {
    echo "apple does not exist in array";
}

In the above code, we first create an array containing three elements: "apple", "banana" and "orange". Then we use the in_array() function to determine whether the "apple" element is in the array and output the corresponding result.

But sometimes, what we need to determine is whether an element is not in the array. At this time we can use the logical operator! (negation) to achieve this.

For example, the code is as follows:

$arr = array('apple', 'banana', 'orange');
if (!in_array('pear', $arr)) {
    echo "pear does not exist in array";
} else {
    echo "pear exists in array";
}

In the above code, we search for "pear" in the array and use the logical operator! to determine whether it does not exist in the array.

In addition to the above methods, we can also use the array_search() function to find the subscript of the element in the array. This function returns the subscript value of the element in the array, or FALSE if it cannot be found. Therefore, we can use the logical operator! to determine whether an element is not in the array.

For example, the code is as follows:

$arr = array('apple', 'banana', 'orange');
if (!array_search('pear', $arr)) {
    echo "pear does not exist in array";
} else {
    echo "pear exists in array";
}

The above is an introduction to the judgment that PHP elements are not in the array. Whether you use the in_array() function or the array_search() function, you can easily determine whether an element is in the array or not. Developers can choose the appropriate method based on specific circumstances.

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