How to Get the Last Digit of an Integer in PHP?

In PHP, you can get the last digit of an integer in the following ways:

• Using Modulo Operator;
• Converting to String and Returning Last Character.

Using Modulo Operator

You can use the modulo operator (%) to get the last digit of an integer in the following way:

function lastDigit(int $num): int
{
    return $num % 10;
}

var_dump(lastDigit(0)); // 0
var_dump(lastDigit(1234)); // 4
var_dump(lastDigit(-1234)); // -4

In the example above, the modulo operator (%) works by dividing a given number by 10 and returning the remainder. It uses truncated division, and is equivalent to the following:

function lastDigit(int $num): int
{
    $quotient = intdiv($num, 10);
    return ($num - (10 * $quotient));
}

var_dump(lastDigit(0)); // 0
var_dump(lastDigit(1234)); // 4
var_dump(lastDigit(-1234)); // -4

This works in the following way:

// num = 1234

// lastDigit = 1234 - (10 * intdiv(1234, 10))
// lastDigit = 1234 - (10 * 123)
// lastDigit = 1234 - 1230
// lastDigit = 4

Converting to String and Returning Last Character

You could do the following:

1. Convert the integer to a string;
2. Get the last character of the string;
3. Convert the string back to integer;
4. Add negative sign to the last digit if integer was negative.

// PHP 7.1+
function lastDigit(int $num): int
{
    $numStr = (string) $num;
    $lastChar = $numStr[-1];
    $lastDigitUnsigned = (int) $lastChar;

    return ($num < 0) ? -$lastDigitUnsigned : $lastDigitUnsigned;
}

var_dump(lastDigit(0)); // 0
var_dump(lastDigit(1234)); // 4
var_dump(lastDigit(-1234)); // -4

To support versions prior to PHP 7.1, you can use $numStr[strlen($numStr) - 1] instead of $numStr[-1].