PHP Comparing two arrays in an conditional statement

Question

I have two arrays and I want to compare the first with the second array. I have an IF statement and it currently does two checks:

It checks to see if there are any rows from my query
If the above passes, then I want to traverse the array values of the first array and compare it with the second array. I want to traverse through all the names first array (index 0-9) and compare it with the first name of the second array (index 0). Keep doing the same thing until we've compared all the indices 0-9 on the first array with all indices 0-9 of the second array.
Finally, if there is a match I want to exit my PHP script, else if there is no match I continue to do to stuff.

I have tried using the in_array() function and that works, but only with a single variable. Something like this in_array($firstArray[0], $secondArray) works. Something like this:

    if(mysqli_num_rows($result) > 0 && in_array($firstArray[0], $secondArray)){
        exit("exiting now!");
    } 
    else {
        echo "continue to do stuff...";
    }

However, when I put the whole array in the inArray, it won't work. Like this:

in_array($firstArray, $secondArray)

How can I achieve this?

You state: "Something like this in_array($firstArray[0], $secondArray) works." --- But then state: "However, when I put the whole array in the inArray, it won't work. Like this: in_array($firstArray[0], $secondArray)" - There's something I'm not grasping and there's something you're probably not showing us/telling us and that would be the query itself and/or the value of the arrays. Edit: This comment was based on the original post stackoverflow.com/revisions/46333586/1 — Funk Forty Niner
– Funk Forty Niner, Commented Sep 21, 2017 at 0:28

Hameed · Accepted Answer · 2017-10-10 04:19:37Z

2

You can use array_intersect if you want to know if they intersect, you can use array_diff to see if the two arrays have any differences.

if(mysqli_num_rows($result) > 0 && !array_diff($firstArray, $secondArray)){
       exit("exiting now!");
} else {
       echo "continue to do stuff...";
}

Example:

<?php
$array1 = array (1,2,3,4);
$array2 = array (3,2,1,5);
$array3 = array_diff($array1, $array2);
$array4 = array_intersect($array1, $array2);
echo "<pre>";
echo "Array 1\n ";
print_r($array1);
echo "Array 2\n ";
print_r($array2);

echo "Arrays Difference \n ";
print_r($array3);
echo "Arrays intersect \n ";
print_r($array4);
echo "</pre>";
?>

Output:

Array 1
 Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
)
Array 2
 Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 5
)
Arrays Difference 
 Array
(
    [3] => 4
)
Arrays intersect 
 Array
(
    [0] => 1
    [1] => 2
    [2] => 3
)

edited Oct 10, 2017 at 4:19

answered Sep 21, 2017 at 0:42

Hameed

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7 Comments

tiger_groove Over a year ago

Does it return a boolean true or false that can be used in my conditional?

Hameed Over a year ago

Did you click on the links? It gives proper example. You can use if (array_diff($blah, $lbah))

tiger_groove Over a year ago

The return value is not a boolean.

tiger_groove Over a year ago

Returns an array containing all the entries from array1 that are not present in any of the other arrays. So in order to use it in a conditional i will need to create my own function right?

Hameed Over a year ago

In PHP, an empty array evaluates to false. so !array_diff means they have the same content. Booleans in php

|

nathan hayfield · Accepted Answer · 2017-09-21 00:43:51Z

1

I think you are looking for array_intersect() which returns the values that are common in two (or more) arrays. http://php.net/manual/en/function.array-intersect.php

It returns an array but if it returns an empty array then empty arrays are falsy.

edited Sep 21, 2017 at 0:43

answered Sep 21, 2017 at 0:41

nathan hayfield

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1 Comment

tiger_groove Over a year ago

Does it return a boolean true or false that can be used in my conditional?

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