Escale any dollar signs when formatting cell data

When a cell is formatted as text and contains a number prefixed with dollar sign, this number is getting replaced with 0. The replacement happens due to the preg_replace function.
This commit escapes any sollar signs on the cell data, so those are not replaced.

src/PhpSpreadsheet/Style/NumberFormat/Formatter.php

@@ -126,7 +126,10 @@ public static function toFormattedString($value, string $format, ?array $callBac
         // For now we do not treat strings in sections, although section 4 of a format code affects strings
         // Process a single block format code containing @ for text substitution
         if (preg_match(self::SECTION_SPLIT, $format) === 0 && preg_match(self::SYMBOL_AT, $format) === 1) {
-            return str_replace('"', '', preg_replace(self::SYMBOL_AT, (string) $value, $format) ?? '');
+            //escape any dollar signs on the string, so they are not replaced with an empty value
+            $value = str_replace('$', '\\$', (string) $value);
+
+            return str_replace('"', '', preg_replace(self::SYMBOL_AT, $value, $format) ?? '');
         }
 
         // If we have a text value, return it "as is"

tests/PhpSpreadsheetTests/Worksheet/ToArrayTest.php

@@ -4,6 +4,7 @@
 
 namespace PhpOffice\PhpSpreadsheetTests\Worksheet;
 
+use PhpOffice\PhpSpreadsheet\Reader\Xlsx;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
 use PHPUnit\Framework\TestCase;
 
@@ -76,4 +77,19 @@ public static function testMaxCol(): void
         self::assertSame('start', $array[0][0]);
         self::assertSame('end', $array[0][16383]);
     }
+
+    public static function testDollarSign(): void
+    {
+        $filename = 'tests/data/Reader/XLSX/issue.4242.xlsx';
+        $reader = new Xlsx();
+        $spreadsheet = $reader->load($filename);
+        $sheet = $spreadsheet->getActiveSheet();
+
+        $expected = [
+            ['General', '$0', 'Value is $100', '200 number - $200 value', null],
+            ['Text', '$0', 'Value is $100', '200 number - $200 value', null],
+        ];
+        $result = $sheet->toArray();
+        self::assertSame($expected, $result);
+    }
 }