PHP check if variable is a whole number

Question

I have this PHP code:

$entityElementCount = (-($highScore-$totalKeywordCount))/0.29;

What i want to know is, how to check whether $

Answer 1

I tested all the proposed solutions with many problematic values mentioned, they all fail for at least one of the test cases. Start checking if $value is a number using is_numeric($value) reduces the number of failures for many solutions, but does not turn any solution into an ultimate one:

$test_cases = array(0.29, 2, 6, 2.33, 6.2, '10.00', 1.4, 10, "10", 10.5, "0x539", true,
    false, 0x53, 9.4, "ten", "100", 1, 0.999999997, 0, 0.0001, 1.0, 0.9999999,
    (-(4.42-5))/0.29);

function is_whole_number($value) {
    // Doing this prevents failing for values like true or "ten"
    if (!is_numeric($value)) {
        return false;
    }

    // @ghostdog74's solution fails for "10.00"
    // return (ctype_digit((string) $value));

    // Both @Maurice's solutions fails for "10.00"
    // return ((string) $value === (string) (int) $value);
    // return is_int($value);

    // @j.hull's solution always returns true for numeric values
    // return (abs($value) % 1 == 0 ? true : false);

    // @ MartyIX's solution fails for "10.00"
    // return ($value === intval($value));

    // This one fails for (-(4.42-5))/0.29
    // return (floor($value) == $value);

    // This one fails for 2
    // return ctype_digit($value);

    // I didn't understand Josh Crozier's answer

    // @joseph4tw's solution fails for (-(4.42-5))/0.29
    // return !(fmod($value, 1) != 0);

    // If you are unsure about the double negation, doing this way produces the same
    // results:
    // return (fmod($value, 1) == 0);

    // Doing this way, it always returns false 
    // return (fmod($value, 1) === 0);

    // @Anthony's solution fails for "10.00"
    // return (is_numeric($value) && is_int($value));

    // @Aistina's solution fails for 0.999999997
    // return (abs($value - round($value)) < 0.0001);

    // @Notinlist's solution fails for 0.999999997
    // return (round($value, 3) == round($value));
}

foreach ($test_cases as $test_case) {
    var_dump($test_case);
    echo ' is a whole number? ';
    echo is_whole_number($test_case) ? 'yes' : 'no';
    echo "\n";
}

I think that solutions like the ones proposed by @Aistina and @Notinlist are the best ones, because they use an error threshold to decide whether a value is a whole number. It is important to note that they worked as expected for the expression (-(4.42-5))/0.29, while all the others failed in that test case.

I decided to use @Notinlist's solution because of its readability:

function is_whole_number($value) {
    return (is_numeric($value) && (round($value, 3) == round($value)));
}

I need to test if values are whole numbers, currency or percentage, I think 2 digits of precision is enough, so @Notinlist's solution fits my needs.

Running this test:

$test_cases = array(0.29, 2, 6, 2.33, 6.2, '10.00', 1.4, 10, "10", 10.5, "0x539", true,
    false, 0x53, 9.4, "ten", "100", 1, 0.999999997, 0, 0.0001, 1.0, 0.9999999,
    (-(4.42-5))/0.29);

function is_whole_number($value) {
    return (is_numeric($value) && (round($value, 3) == round($value)));
}

foreach ($test_cases as $test_case) {
    var_dump($test_case);
    echo ' is a whole number? ';
    echo is_whole_number($test_case) ? 'yes' : 'no';
    echo "\n";
}

Produces the following output:

float(0.29)
 is a whole number? no
int(2)
 is a whole number? yes
int(6)
 is a whole number? yes
float(2.33)
 is a whole number? no
float(6.2)
 is a whole number? no
string(5) "10.00"
 is a whole number? yes
float(1.4)
 is a whole number? no
int(10)
 is a whole number? yes
string(2) "10"
 is a whole number? yes
float(10.5)
 is a whole number? no
string(5) "0x539"
 is a whole number? yes
bool(true)
 is a whole number? no
bool(false)
 is a whole number? no
int(83)
 is a whole number? yes
float(9.4)
 is a whole number? no
string(3) "ten"
 is a whole number? no
string(3) "100"
 is a whole number? yes
int(1)
 is a whole number? yes
float(0.999999997)
 is a whole number? yes
int(0)
 is a whole number? yes
float(0.0001)
 is a whole number? yes
float(1)
 is a whole number? yes
float(0.9999999)
 is a whole number? yes
float(2)
 is a whole number? yes