Question

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Converting words to numbers in PHP

Is there a php function to convert a string such as ‘ten’ into an integer?
If not then how would you go about it?
Have tried google and php.net search with no success

Answer 1

Here’s a proof of concept class that I just wrote to do this… Check it out:

class WordToNumber {

    public $modifiers = array(
        'hundred' => 100,
    );

    public $negatives = array(
        'minus' => true,
        'negative' => true,
    );

    public $numbers = array(
        'zero'  => 0,
        'one'   => 1,
        'two'   => 2,
        'three' => 3,
        'four'  => 4,
        'five'  => 5,
        'six'   => 6,
        'seven' => 7,
        'eight' => 8,
        'nine'  => 9,
        'ten'   => 10,
        'eleven' => 11,
        'twelve' => 12,
        'thirteen' => 13,
        'fourteen' => 14,
        'fifteen'  => 15,
        'sixteen'  => 16,
        'seventeen' => 17,
        'eighteen'  => 18,
        'nineteen'  => 19,
        'twenty'    => 20,
        'thirty'    => 30,
        'forty'    => 40,
        'fifty'     => 50,
        'sixty'     => 60,
        'seventy'   => 70,
        'eighty'    => 80,
        'ninety'    => 90,    
    );

    public $powers = array(
        'thousand' => 1000,
        'million'  => 1000000,
        'billion'  => 1000000000,
    );

    public function __construct() {
    }

    public function parse($string) {
        $string = $this->prepare($string);
        $parts = preg_split('#\s+#', $string, -1, PREG_SPLIT_NO_EMPTY);
        $buffer = 0;
        $lastPower = 1;
        $powers = array(
            1 => 0,
        );
        $isNegative = false;
        foreach ($parts as $part) {
            if (isset($this->negatives[$part])) {
                $isNegative = true;
            } elseif (isset($this->numbers[$part])) {
                $buffer += $this->numbers[$part];
            } elseif (isset($this->modifiers[$part])) {
                $buffer *= $this->modifiers[$part];
            } elseif (isset($this->powers[$part])) {
                if ($buffer == 0) {
                    //Modify last power
                    $buffer = $powers[$lastPower];
                    unset($powers[$lastPower]);
                    $power = $lastPower * $this->powers[$part];
                    $powers[$power] = $buffer;
                    $lastPower = $power;
                    $buffer = 0;
                } else {
                    $powers[$this->powers[$part]] = $buffer;
                    $buffer = 0;
                    $lastPower = $this->powers[$part];
                }
            } else {
                throw new LogicException('Unknown Token Found: '.$part);
            }
        }
        if (!empty($buffer)) {
            $powers[1] = $buffer;
        }
        $total = 0;
        foreach ($powers as $power => $sub) {
            $total += $power * $sub;
        }
        if ($isNegative) {
            $total *= -1;
        }
        return $total;
    }

    protected function prepare($string) {
        $string = preg_replace('#(\s+|-|\band\b)#i', ' ', $string);
        $string = mb_convert_case($string, MB_CASE_LOWER);
        return $string;
    }

}

And a test:

$parser = new WordToNumber();

$strings = array(
    'one hundred and fifty two',
    'fifteen',
    'one thousand million',
    'four hundred thousand five hundred fourty three',
    'fifteen hundred',
    'one thousand twelve hundred',
    'negative two',
    'minus three hundred and fifty seven thousand four hundred and two',
);

foreach ($strings as $str) {
    echo $parser->parse($str).' - '.$str."\n";
}

And the results:

152 - one hundred and fifty two
15 - fifteen
1000000000 - one thousand million
400543 - four hundred thousand five hundred fourty three
1500 - fifteen hundred
2200 - one thousand twelve hundred
-2 - negative two
-357402 - minus three hundred and fifty seven thousand four hundred and two

It doesn’t support huge numbers (hence why billion is the largest power), but it should be trivially modified to support them by using the bcmath extension… If you want, I could quickly modify it to work with numbers as high as you want.