PHP Exercises: Create a function that returns true for all elements of an array, false otherwise

Last update on April 19 2025 11:50:22 (UTC/GMT +8 hours)

78. Array All-True Checker

Write a PHP program to create a function that returns true for all elements of an array, false otherwise.

Sample Solution:

PHP Code:

<?php
// Function definition for 'test_all' that takes an array of items and a custom function as parameters
function test_all($items, $my_func)
{
    // Check if the count of items passing the custom function is equal to the total count of items
    if (count(array_filter($items, $my_func)) === count($items))
        // If all items pass the condition, return 1 (true)
        return 1;
    else
        // If at least one item fails the condition, return 0 (false)
        return 0;
}

// Call 'test_all' with an array of positive numbers and a custom function checking if each item is greater than 0
echo test_all([2, 3, 4, 5], function ($item) {return $item > 0;});
// Display a newline
echo "\n";

// Call 'test_all' with an array of negative numbers and a custom function checking if each item is greater than 0
echo test_all([-2, -3, -4, -5], function ($item) {return $item > 0;});
// Display a newline
echo "\n";

// Call 'test_all' with an array of mixed positive and negative numbers and a custom function checking if each item is greater than 0
echo test_all([-2, 3, 4, -5], function ($item) {return $item > 0;});

?>

Explanation:

Define test_all Function:

The function test_all takes an array of items ($items) and a custom function ($my_func) as parameters.

Check If All Items Meet a Condition:

Uses array_filter to apply $my_func to each item in $items, creating a filtered array of items that pass the condition.
Compares the count of items that pass the condition with the total count of $items.
If all items pass (filtered count equals original count), returns 1 (true).
If at least one item fails, returns 0 (false).

Test with an Array of Positive Numbers:

Calls test_all with [2, 3, 4, 5] and a function that checks if each item is greater than 0.
Since all items are positive, test_all returns 1, indicating that all items pass the condition.

Test with an Array of Negative Numbers:

Calls test_all with [-2, -3, -4, -5] and the same condition.
Since all items are negative, test_all returns 0, indicating that none of the items pass the condition.

Test with a Mixed Array:

Calls test_all with [-2, 3, 4, -5] and the same condition.
Since not all items are positive, test_all returns 0.

Output:

1
0
0

Flowchart:

For more Practice: Solve these Related Problems:

Write a PHP function to check if all elements in an array satisfy a given condition and return true if they do.
Write a PHP script to iterate over an array and determine if every element evaluates as truthy.
Write a PHP script to validate that each element in a user-defined array passes a custom boolean test.
Write a PHP script to create a callback that returns true only if all items in an array are non-falsy values.

PHP Code Editor:

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