Additional Floating Point Precision Changes

Fix PHPOffice#1324, which went stale many years ago, and is now re-opened. It can be considered a follow-on to PR PHPOffice#4479 which was installed in May. The user complains of a *very* small loss of precision. This can be corrected by using `StringHelper::convertToString` in lieu of a simple cast from float to string in two places. `Style\NumberFormat\Formatter` is quite straightforward. `Writer\Csv` is a bit more complicated. If you put a float with more than 15 digits precision in a Csv, on opening it Excel will give a pop-up, saying something inaccurate like "We've corrected this for you - is that okay?" Better to avoid that by making sure to avoid too much precision when writing to Csv.

Author: oleibman

src/PhpSpreadsheet/Style/NumberFormat/Formatter.php

@@ -159,7 +159,9 @@ public static function toFormattedString($value, string $format, null|array|call
         // For 'General' format code, we just pass the value although this is not entirely the way Excel does it,
         // it seems to round numbers to a total of 10 digits.
         if (($format === NumberFormat::FORMAT_GENERAL) || ($format === NumberFormat::FORMAT_TEXT)) {
-            return self::adjustSeparators((string) $value);
+            return self::adjustSeparators(
+                StringHelper::convertToString($value)
+            );
         }
 
         // Ignore square-$-brackets prefix in format string, like "[$-411]ge.m.d", "[$-010419]0%", etc

src/PhpSpreadsheet/Writer/Csv.php

@@ -2,10 +2,10 @@
 
 namespace PhpOffice\PhpSpreadsheet\Writer;
 
+use Composer\Pcre\Preg;
 use PhpOffice\PhpSpreadsheet\Calculation\Calculation;
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
-use Stringable;
 
 class Csv extends BaseWriter
 {
@@ -133,6 +133,7 @@ public function save($filename, int $flags = 0): void
                     }
                 }
             }
+            /** @var string[] $cellsArray */
             $this->writeLine($this->fileHandle, $cellsArray);
         }
 
@@ -271,25 +272,11 @@ public function getEnclosureRequired(): bool
         return $this->enclosureRequired;
     }
 
-    /**
-     * Convert boolean to TRUE/FALSE; otherwise return element cast to string.
-     *
-     * @param null|bool|float|int|string|Stringable $element element to be converted
-     */
-    private static function elementToString(mixed $element): string
-    {
-        if (is_bool($element)) {
-            return $element ? 'TRUE' : 'FALSE';
-        }
-
-        return (string) $element;
-    }
-
     /**
      * Write line to CSV file.
      *
      * @param resource $fileHandle PHP filehandle
-     * @param mixed[] $values Array containing values in a row
+     * @param string[] $values Array containing values in a row
      */
     private function writeLine($fileHandle, array $values): void
     {
@@ -299,9 +286,23 @@ private function writeLine($fileHandle, array $values): void
         // Build the line
         $line = '';
 
-        /** @var null|bool|float|int|string|Stringable $element */
         foreach ($values as $element) {
-            $element = self::elementToString($element);
+            if (Preg::isMatch('/^([+-])?(\d+)[.](\d+)/', $element, $matches)) {
+                // Excel will "convert" file with pop-up
+                // if there are more than 15 digits precision.
+                $whole = $matches[2];
+                if ($whole !== '0') {
+                    $wholeLen = strlen($whole);
+                    $frac = $matches[3];
+                    $maxFracLen = 15 - $wholeLen;
+                    if ($maxFracLen >= 0 && strlen($frac) > $maxFracLen) {
+                        $result = sprintf("%.{$maxFracLen}F", $element);
+                        if (str_contains($result, '.')) {
+                            $element = Preg::replace('/[.]?0+$/', '', $result); // strip trailing zeros
+                        }
+                    }
+                }
+            }
             // Add delimiter
             $line .= $delimiter;
             $delimiter = $this->delimiter;

tests/PhpSpreadsheetTests/Shared/Issue1324Test.php

@@ -0,0 +1,48 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpOffice\PhpSpreadsheetTests\Shared;
+
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+use PhpOffice\PhpSpreadsheet\Writer\Csv as CsvWriter;
+use PhpOffice\PhpSpreadsheetTests\Functional\AbstractFunctional;
+
+class Issue1324Test extends AbstractFunctional
+{
+    protected static int $version = 80400;
+
+    public function testPrecision(): void
+    {
+        $string1 = '753.149999999999';
+        $s1 = (float) $string1;
+        $spreadsheet = new Spreadsheet();
+        $sheet = $spreadsheet->getActiveSheet();
+        $sheet->getCell('A1')->setValue($s1);
+        self::assertNotSame(753.15, $sheet->getCell('A1')->getValue());
+        $formats = ['Csv', 'Xlsx', 'Xls', 'Ods', 'Html'];
+        foreach ($formats as $format) {
+            $reloadedSpreadsheet = $this->writeAndReload($spreadsheet, $format);
+            $rsheet = $reloadedSpreadsheet->getActiveSheet();
+            $s2 = $rsheet->getCell('A1')->getValue();
+            self::assertSame($s1, $s2, "difference for $format");
+            $reloadedSpreadsheet->disconnectWorksheets();
+        }
+        $spreadsheet->disconnectWorksheets();
+    }
+
+    public function testCsv(): void
+    {
+        $string1 = '753.149999999999';
+        $s1 = (float) $string1;
+        $spreadsheet = new Spreadsheet();
+        $sheet = $spreadsheet->getActiveSheet();
+        $sheet->getCell('A1')->setValue($s1);
+        $writer = new CsvWriter($spreadsheet);
+        ob_start();
+        $writer->save('php://output');
+        $output = (string) ob_get_clean();
+        self::assertStringContainsString($string1, $output);
+        $spreadsheet->disconnectWorksheets();
+    }
+}