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<?php class Fraction { const FRACTION_RATIO_ADJUST = true; const FRACTION_RATIO_KEEP = false; const FRACTION_FORMAT_DELIMITER = '/'; private $value = []; public function __construct($x, $y, $adjustRatio=self::FRACTION_RATIO_KEEP) { if(!is_int($x) || !is_int($y) || !$y) { throw InvalidArgumentException('Invalid fraction parts'); } $sign = ($x>0&&$y>0) || ($x<0&&$y<0)?1:-1; $this->value = ['numerator'=>$sign*$x, 'denominator'=>abs($y)]; if($adjustRatio==self::FRACTION_RATIO_ADJUST) { $this->adjustRatio(); } } public function getNumerator() { return $this->value['numerator']; } public function getDenominator() { return $this->value['denominator']; } public function adjustRatio() { $gcd = (int)gmp_strval(gmp_gcd( (string)$this->getNumerator(), (string)$this->getDenominator())); $this->setFraction([ 'numerator' => $this->getNumerator()/$gcd, 'denominator' => $this->getDenominator()/$gcd ]); } public function add(self $fraction, $adjustRatio=self::FRACTION_RATIO_KEEP) { $numerator = $this->getNumerator()*$fraction->getDenominator() + $this->getDenominator()*$fraction->getNumerator(); $denominator = $this->getDenominator()*$fraction->getDenominator(); $this->setFraction([ 'numerator' => $numerator, 'denominator' => $denominator ]); if($adjustRatio==self::FRACTION_RATIO_ADJUST) { $this->adjustRatio(); } } public function format() { $denominator = $this->getDenominator(); $numerator = $this->getNumerator(); return $denominator==1? (string)$numerator: (string)($numerator.self::FRACTION_FORMAT_DELIMITER.$denominator); } public function __toString() { return $this->format();//may be other } private function setFraction(array $data) { if(!array_key_exists('numerator', $data) || !array_key_exists('denominator', $data)) { throw InvalidArgumentException('Invalid data structure used in direct set'); } if(!is_int($data['numerator']) || !is_int($data['denominator']) || !$data['denominator']) { throw InvalidArgumentException('Invalid fraction data used in direct set'); } $this->value['numerator'] = $data['numerator']; $this->value['denominator'] = $data['denominator']; } } $fraction = new Fraction(8, -12, Fraction::FRACTION_RATIO_KEEP); echo($fraction->format());//-8/12 $fraction->add(new Fraction(1, 3), Fraction::FRACTION_RATIO_ADJUST); echo($fraction->format());//-1/3