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PHP Big Integer Implementation - V1
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‎Algorithms/Numbers-Maths/BigNumber.php‎

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<?php
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/*
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* Author: Mizanur rahman <[email protected]>
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*
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* Actual algorithm from: Steven Skiena
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*/
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define("MAXDIGITS", 1000);
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define("PLUS", 1);
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define("MINUS", -1);
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class BigInteger
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{
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public $digits;
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public $lastDigit;
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public $signBit;
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public function __construct(string $number)
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{
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if (strlen($number) == 0) throw new Exception("Number must be present");
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if (!preg_match("/(-)?(\d)*/", $number)) {
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throw new Exception("Only valid digits are allowed");
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}
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$this->signBit = PLUS;
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if ($number[0] == "-")
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$this->signBit = MINUS;
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for ($i = 0; $i < MAXDIGITS; $i++) $this->digits[$i] = 0;
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$this->lastDigit = -1;
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for ($t = strlen($number); $t > 0; $t--) {
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$this->lastDigit++;
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$this->digits[$this->lastDigit] = $number[$t - 1];
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}
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if ($number == "0") $this->lastDigit = 0;
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}
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}
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function printBigInteger(BigInteger &$n)
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{
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if ($n->signBit == MINUS) echo "- ";
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for ($i = $n->lastDigit; $i >= 0; $i--)
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echo $n->digits[$i];
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echo "\n";
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}
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function intToBigInteger(string $s, BigInteger &$n)
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{
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if ($s >= 0)
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$n->signBit = PLUS;
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else
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$n->signBit = MINUS;
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for ($i = 0; $i < MAXDIGITS; $i++) $n->digits[$i] = 0;
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$n->lastDigit = -1;
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$t = abs($s);
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while ($t > 0) {
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$n->lastDigit++;
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$n->digits[$n->lastDigit] = ($t % 10);
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$t /= 10;
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}
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if ($s == 0) $n->lastDigit = 0;
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}
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function initBigInteger(BigInteger &$n)
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{
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intToBigInteger(0, $n);
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}
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function zeroJustify(BigInteger &$n)
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{
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while (($n->lastDigit > 0) && ($n->digits[$n->lastDigit] == 0))
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$n->lastDigit--;
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if (($n->lastDigit == 0) && ($n->digits[0] == 0))
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$n->signBit = PLUS; /* hack to avoid -0 */
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}
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function digitShift(BigInteger $n, int $d) /* multiply n by 10^d */
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{
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if (($n->lastDigit == 0) && ($n->digits[0] == 0)) return;
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for ($i = $n->lastDigit; $i >= 0; $i--)
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$n->digits[$i + $d] = $n->digits[$i];
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for ($i = 0; $i < $d; $i++) $n->digits[$i] = 0;
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$n->lastDigit = $n->lastDigit + $d;
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}
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function compareBigInteger(BigInteger &$a, BigInteger &$b)
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{
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if (($a->signBit == MINUS) && ($b->signBit == PLUS)) return (PLUS);
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if (($a->signBit == PLUS) && ($b->signBit == MINUS)) return (MINUS);
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if ($b->lastDigit > $a->lastDigit) return (PLUS * $a->signBit);
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if ($a->lastDigit > $b->lastDigit) return (MINUS * $a->signBit);
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for ($i = $a->lastDigit; $i >= 0; $i--) {
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if ($a->digits[$i] > $b->digits[$i]) return (MINUS * $a->signBit);
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if ($b->digits[$i] > $a->digits[$i]) return (PLUS * $a->signBit);
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}
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return 0;
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}
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function addBigInteger(BigInteger &$a, BigInteger &$b, BigInteger &$c)
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{
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initBigInteger($c);
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if ($a->signBit == $b->signBit)
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$c->signBit = $a->signBit;
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else {
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if ($a->signBit == MINUS) {
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$a->signBit = PLUS;
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subtractBigInteger($b, $a, $c);
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$a->signBit = MINUS;
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} else {
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$b->signBit = PLUS;
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subtractBigInteger($a, $b, $c);
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$b->signBit = MINUS;
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}
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return;
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}
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$c->lastDigit = max($a->lastDigit, $b->lastDigit) + 1;
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$carry = 0;
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for ($i = 0; $i <= $c->lastDigit; $i++) {
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$c->digits[$i] = ($carry + $a->digits[$i] + $b->digits[$i]) % 10;
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$carry = intval(($carry + $a->digits[$i] + $b->digits[$i]) / 10);
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}
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zeroJustify($c);
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}
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function subtractBigInteger(BigInteger &$a, BigInteger &$b, BigInteger &$c)
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{
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initBigInteger($c);
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if (($a->signBit == MINUS) || ($b->signBit == MINUS)) {
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$b->signBit = -1 * $b->signBit;
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addBigInteger($a, $b, $c);
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$b->signBit = -1 * $b->signBit;
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return;
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}
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if (compareBigInteger($a, $b) == PLUS) {
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subtractBigInteger($b, $a, $c);
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$c->signBit = MINUS;
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return;
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}
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$c->lastDigit = max($a->lastDigit, $b->lastDigit);
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$borrow = 0;
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for ($i = 0; $i <= ($c->lastDigit); $i++) {
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$v = ($a->digits[$i] - $borrow - $b->digits[$i]);
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if ($a->digits[$i] > 0)
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$borrow = 0;
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if ($v < 0) {
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$v = $v + 10;
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$borrow = 1;
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}
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$c->digits[$i] = $v % 10;
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}
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zeroJustify($c);
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}
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function multiplyBigInteger(BigInteger &$a, BigInteger &$b, BigInteger &$c)
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{
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$numbers = [];
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for ($i = 0; $i <= $b->lastDigit; $i++) {
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$carry = 0;
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$tmp = clone $c;
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$tmp->lastDigit = 0;
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for ($j = 0; $j <= $a->lastDigit; $j++) {
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$tmp->digits[$tmp->lastDigit++] = ($carry + $a->digits[$j] * $b->digits[$i]) % 10;
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$carry = intval(($carry + $a->digits[$j] * $b->digits[$i]) / 10);
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}
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if ($carry > 0) {
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$tmp->digits[$tmp->lastDigit] = $carry;
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}
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digitShift($tmp, $i);
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zeroJustify($tmp);
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$numbers[] = $tmp;
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}
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foreach ($numbers as $number) {
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$tmp = clone $c;
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addBigInteger($number, $tmp, $c);
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}
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$c->signBit = $a->signBit * $b->signBit;
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zeroJustify($c);
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}
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function divideBigInteger(BigInteger &$a, BigInteger &$b, BigInteger &$c)
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{
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$row = clone $c;
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$tmp = clone $c;
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$c->signBit = $a->signBit * $b->signBit;
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$asign = $a->signBit;
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$bsign = $b->signBit;
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$a->signBit = PLUS;
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$b->signBit = PLUS;
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$c->lastDigit = $a->lastDigit;
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for ($i = $a->lastDigit; $i >= 0; $i--) {
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digitShift($row, 1);
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$row->digits[0] = $a->digits[$i];
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$c->digits[$i] = 0;
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while (compareBigInteger($row, $b) != PLUS) {
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$c->digits[$i]++;
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subtractBigInteger($row, $b, $tmp);
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$row = clone $tmp;
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}
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}
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zeroJustify($c);
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$a->signBit = $asign;
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$b->signBit = $bsign;
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}
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function factorial (int $n, BigInteger &$c) {
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intToBigInteger("1", $c);
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if($n > 0) {
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for($i = 1;$i<=$n;$i++) {
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$tmp = clone $c;
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$number = new BigInteger($i);
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$result = new BigInteger("0");
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multiplyBigInteger($number, $tmp, $result);
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$c = $result;
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}
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}
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zeroJustify($c);
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}
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$first = new BigInteger("12345678");
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$second = new BigInteger("2222");
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$result = new BigInteger("0");
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printBigInteger($first);
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printBigInteger($second);
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//divideBigInteger($first, $second, $result);
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$start = microtime(false);
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factorial(100, $result);
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$end = microtime(false);
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printBigInteger($result);
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‎README.md‎

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# PHP-Data-Structure-and-Algorithms
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# PHP Data Structures and Algorithms
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Data structure and Algorithm is always important for any programming language. PHP, being one of the most popular language for web development, also requires the pure data structure and algorithm implementations.
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