Is value in array php?

From the course: PHP for Web Designers

Table of Contents Show

Finding if a value exists in an array
4.11. Checking if an Element Is in an Array
Is in array value PHP?
How do you check if a variable is in an array PHP?
How do you check if a value is present in an array?
How do you get a specific value from an array in PHP?

Finding if a value exists in an array

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Sometimes it's useful to find if a particular value exists in an array. One way to do so, is to use a loop to check the value of each array element. But that's inefficient. A much quicker and simpler way, is to use a function called, in array. To see how it works, let's use the indexed array, flowers, which is at the top of this page on lines two and three. The in array function takes two arguments. The value you're looking for and the array you want to examine. Well the array we want to examine is called flowers, and let's choose daffodils. We need to choose a value that we know is going to be there as a good test of whether it works or not. So, let's go down into the HTML. And under the h2 element, let's create a php block. And the first thing we need to do inside there is to create a variable to stall the value we're looking for. The variable I'm going to use, I'm going to call it, order equals daffodils. And then we need an if-else structure to test whether daffodils is in that array. So if and then the condition, and the condition will be in_array and then the two variables, the two arguments that we need to pass to it. The first one is what we're looking for, so that's order, and the second argument is the array we want to inspect, and that's flowers. Closing parenthesis there for in_array. We need a second closing parenthesis for the condition, and then we need a pair of curly braces for the conditional block. And inside there, if it exists we want to display, so we can use echo and would use a double quoted string, have a paragraph and, Yes order are in stock. And then if it fails, we need an else, clause. So else and then that, block down there. And inside there, we'll do echo. And then a little paragraph. Sorry, no order available. So, if we save that page we can now test it in a browser and that will tell us whether daffodils is actually in the flowers array. So we need to go to the zero, nine folder. An the name of the page, is in_array.php. And yes, daffodils are in stock. So let's see what happens if, you choose something that's not there. If we change daffodils to a flower that we know is not in that array. Definitely marigolds are not there. So save that and then go back to the browser, refresh it, Sorry no marigolds available. So, that's how you find out whether a particular value exists in an array. You use the in array function and it takes two arguments. The first argument is the value that you're looking for and the second one is the array that you're looking in. And a useful way to remember the correct order of the arguments is, you're looking for a needle in the haystack and if the needle is in the haystack in array returns true if it's not there, it returns false.

4.11. Checking if an Element Is in an Array

Problem

You want to know if an array contains a certain value.

Solution

Use in_array( ) :

if (in_array($value, $array)) {
    // an element has $value as its value in array $array
}

Discussion

Use in_array( ) to check if an element of an array holds a value:

$book_collection = array('Emma', 'Pride and Prejudice', 'Northhanger Abbey');
$book = 'Sense and Sensibility';

if (in_array($book, $book_collection) { 
    echo 'Own it.';
} else {
    echo 'Need it.';
}

The default behavior of in_array( ) is to compare items using the == operator. To use the strict equality check, ===, pass true as the third parameter to in_array( ):

$array = array(1, '2', 'three');

in_array(0, $array);        // true!
in_array(0, $array, true);  // false
in_array(1, $array);        // true
in_array(1, $array, true);  // true
in_array(2, $array);        // true
in_array(2, $array, true);  // false

The first check, in_array(0, $array), evaluates to true because to compare the number 0 against the string three, PHP casts three to an integer. Since three isn’t a numeric string, as is 2, it becomes 0. Therefore, in_array( ) thinks there’s a match.

Consequently, when comparing numbers against data that may contain strings, it’s safest to use a strict comparison.

If you find yourself calling in_array( ) multiple times on the same array, it may be better to use an associative array, with the original array elements as the keys in the new associative array. Looking up entries using in_array( ) takes linear time; with an associative array, it takes constant time.

If you can’t create the associative array directly but need to convert from a traditional one with integer keys, use array_flip( ) to swap the keys and values of an array:

$book_collection = array('Emma',
                         'Pride and Prejudice',
                         'Northhanger Abbey');

// convert from numeric array to associative array
$book_collection = array_flip($book_collection);
$book = 'Sense and Sensibility';

if (isset($book_collection[$book])) { 
    echo 'Own it.';
} else {
    echo 'Need it.';
}

Note that doing this condenses multiple keys with the same value into one element in the flipped array.

Is in array value PHP?

The in_array() function is an inbuilt function in PHP that is used to check whether a given value exists in an array or not. It returns TRUE if the given value is found in the given array, and FALSE otherwise.

How do you check if a variable is in an array PHP?

The is_array() function checks whether a variable is an array or not. This function returns true (1) if the variable is an array, otherwise it returns false/nothing.

How do you check if a value is present in an array?

JavaScript Array includes() The includes() method returns true if an array contains a specified value. The includes() method returns false if the value is not found. The includes() method is case sensitive.

How do you get a specific value from an array in PHP?

1. PHP array_search() function. The PHP array_search() is an inbuilt function that is widely used to search and locate a specific value in the given array. If it successfully finds the specific value, it returns its corresponding key value.