Implement BigDecimal::getPrecision()

Fixes #58

Author: BenMorel

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 All notable changes to this project will be documented in this file.
 
+## UNRELEASED (0.12.3)
+
+✨ **New features**
+
+- `BigDecimal::getPrecision()` Returns the number of significant digits in a decimal number
+
 ## [0.12.2](https://github.com/brick/math/releases/tag/0.12.2) - 2025-02-26
 
 ⚡️ **Performance improvements**

src/BigDecimal.php

@@ -571,6 +571,33 @@ public function getScale() : int
         return $this->scale;
     }
 
+    /**
+     * Returns the number of significant digits in the number.
+     *
+     * This is the number of digits to both sides of the decimal point, stripped of leading zeros.
+     * The sign has no impact on the result.
+     *
+     * Examples:
+     *   0 => 0
+     *   0.0 => 0
+     *   123 => 3
+     *   123.456 => 6
+     *   0.00123 => 3
+     *   0.0012300 => 5
+     */
+    public function getPrecision(): int
+    {
+        $value = $this->value;
+
+        if ($value === '0') {
+            return 0;
+        }
+
+        $length = \strlen($value);
+
+        return ($value[0] === '-') ? $length - 1 : $length;
+    }
+
     /**
      * Returns a string representing the integral part of this decimal number.
      *

tests/BigDecimalTest.php

@@ -2247,6 +2247,39 @@ public static function providerSign() : array
         ];
     }
 
+    #[DataProvider('providerGetPrecision')]
+    public function testGetPrecision(string $number, int $precision) : void
+    {
+        self::assertSame($precision, BigDecimal::of($number)->getPrecision());
+        self::assertSame($precision, BigDecimal::of($number)->negated()->getPrecision());
+    }
+
+    public static function providerGetPrecision() : array
+    {
+        return [
+            ['0', 0],
+            ['0.0', 0],
+            ['0.00', 0],
+            ['1', 1],
+            ['12', 2],
+            ['123', 3],
+            ['1.2', 2],
+            ['1.23', 3],
+            ['1.230', 4],
+            ['123.456', 6],
+            ['0.123', 3],
+            ['0.1230', 4],
+            ['0.0123', 3],
+            ['0.01230', 4],
+            ['0.00123', 3],
+            ['0.001230', 4],
+            ['0.0012300', 5],
+            ['1234567890.12345678901234567890123456789012345678901234567890', 60],
+            ['0.0000000000000000000000000000000000000000000000000000000000012345', 5],
+            ['0.00000000000000000000000000000000000000000000000000000000000123450', 6],
+        ];
+    }
+
     /**
      * @param string $number   The number to test.
      * @param string $expected The expected integral value.