function Calculator::fromArbitraryBase

Converts a non-negative number in an arbitrary base using a custom alphabet, to base 10.

Parameters

string $number The number to convert, validated as a non-empty string,: containing only chars in the given alphabet/base.

string $alphabet The alphabet that contains every digit, validated as 2 chars minimum.:

int $base The base of the number, validated from 2 to alphabet length.:

Return value

string The number in base 10, following the Calculator conventions.

1 call to Calculator::fromArbitraryBase()

Calculator::fromBase in vendor/brick/math/src/Internal/Calculator.php

Converts a number from an arbitrary base.

File

vendor/brick/math/src/Internal/Calculator.php, line 363

Class

Calculator

Performs basic operations on arbitrary size integers.

Namespace

Brick\Math\Internal

Code

public final function fromArbitraryBase(string $number, string $alphabet, int $base) : string {
    // remove leading "zeros"
    $number = \ltrim($number, $alphabet[0]);
    if ($number === '') {
        return '0';
    }
    // optimize for "one"
    if ($number === $alphabet[1]) {
        return '1';
    }
    $result = '0';
    $power = '1';
    $base = (string) $base;
    for ($i = \strlen($number) - 1; $i >= 0; $i--) {
        $index = \strpos($alphabet, $number[$i]);
        if ($index !== 0) {
            $result = $this->add($result, $index === 1 ? $power : $this->mul($power, (string) $index));
        }
        if ($i !== 0) {
            $power = $this->mul($power, $base);
        }
    }
    return $result;
}