Omnipay\Common\Message\AbstractRequest::getAmount PHP Method

    public function getAmount()
    {
        $amount = $this->getParameter('amount');
        if ($amount !== null) {
            // Don't allow integers for currencies that support decimals.
            // This is for legacy reasons - upgrades from v0.9
            if ($this->getCurrencyDecimalPlaces() > 0) {
                if (is_int($amount) || is_string($amount) && false === strpos((string) $amount, '.')) {
                    throw new InvalidRequestException('Please specify amount as a string or float, ' . 'with decimal places (e.g. \'10.00\' to represent $10.00).');
                }
            }
            $amount = $this->toFloat($amount);
            // Check for a negative amount.
            if (!$this->negativeAmountAllowed && $amount < 0) {
                throw new InvalidRequestException('A negative amount is not allowed.');
            }
            // Check for a zero amount.
            if (!$this->zeroAmountAllowed && $amount === 0.0) {
                throw new InvalidRequestException('A zero amount is not allowed.');
            }
            // Check for rounding that may occur if too many significant decimal digits are supplied.
            $decimal_count = strlen(substr(strrchr(sprintf('%.8g', $amount), '.'), 1));
            if ($decimal_count > $this->getCurrencyDecimalPlaces()) {
                throw new InvalidRequestException('Amount precision is too high for currency.');
            }
            return $this->formatCurrency($amount);
        }
    }