fix: display fraction for integer values with mandatory 0 placeholder (#3625)

src/PhpSpreadsheet/Style/NumberFormat/FractionFormatter.php

@@ -6,8 +6,13 @@ use PhpOffice\PhpSpreadsheet\Calculation\MathTrig;
 
 class FractionFormatter extends BaseFormatter
 {
-    /** @param null|bool|float|int|string $value  value to be formatted */
-    public static function format(mixed $value, string $format): string
+    /**
+     * @param null|bool|float|int|string $value value to be formatted
+     * @param string $format normalized fraction mask (digit placeholders reduced to ?)
+     * @param ?string $originalFormat unmodified mask, needed to tell mandatory (0)
+     *                                placeholders apart from optional (? #) ones
+     */
+    public static function format(mixed $value, string $format, ?string $originalFormat = null): string
     {
         $format = self::stripQuotes($format);
         $value = (float) $value;
@@ -19,7 +24,7 @@ class FractionFormatter extends BaseFormatter
 
         $decimalPart = self::getDecimal((string) $absValue);
         if ($decimalPart === '0') {
-            return "{$sign}{$integerPart}";
+            return self::integerFraction($sign, (int) $integerPart, $originalFormat ?? $format);
         }
         $decimalLength = strlen($decimalPart);
         $decimalDivisor = 10 ** $decimalLength;
@@ -58,6 +63,37 @@ class FractionFormatter extends BaseFormatter
         return "{$sign}{$adjustedDecimalPart}/{$adjustedDecimalDivisor}";
     }
 
+    /**
+     * Format a value with no fractional remainder. Excel still displays a
+     * fraction when the numerator placeholder uses mandatory digits (0), so
+     * format "0/0" yields "1/1" and "0 0/0" yields "1 0/1"; the "?" and "#"
+     * placeholders suppress the fraction and leave only the integer.
+     */
+    private static function integerFraction(string $sign, int $integerPart, string $format): string
+    {
+        if (preg_match('~(?:([#0?]+)\s+)?([#0?]+)/([#0?]+|\d+)~', $format, $matches) !== 1) {
+            return "{$sign}{$integerPart}";
+        }
+        [, $integerFormat, $numeratorFormat, $denominatorFormat] = $matches;
+        if (!str_contains($numeratorFormat, '0')) {
+            return "{$sign}{$integerPart}";
+        }
+
+        if (preg_match('/[1-9]/', $denominatorFormat) === 1) {
+            $denominator = $denominatorFormat;
+        } else {
+            $denominator = str_pad('1', substr_count($denominatorFormat, '0'), '0', STR_PAD_LEFT);
+        }
+
+        if ($integerFormat !== '') {
+            return "{$sign}{$integerPart} 0/{$denominator}";
+        }
+
+        $numerator = $integerPart * (int) $denominator;
+
+        return "{$sign}{$numerator}/{$denominator}";
+    }
+
     private static function getDecimal(string $value): string
     {
         $decimalPart = '0';

src/PhpSpreadsheet/Style/NumberFormat/NumberFormatter.php

@@ -208,10 +208,11 @@ class NumberFormatter extends BaseFormatter
         $scale = self::scaleThousandsMillions($format);
 
         if (preg_match('/[#\?0]?.*[#\?0]\/(\?+|\d+|#)/', $format)) {
+            $originalFormat = $format;
             // It's a dirty hack; but replace # and 0 digit placeholders with ?
             $format = (string) preg_replace('/[#0]+\//', '?/', $format);
             $format = (string) preg_replace('/\/[#0]+/', '/?', $format);
-            $value = FractionFormatter::format($value, $format);
+            $value = FractionFormatter::format($value, $format, $originalFormat);
         } else {
             // Handle the number itself
             // scale number