PHPOffice · oleibman · Aug 28, 2025 · Aug 28, 2025
diff --git a/README.md b/README.md
@@ -1,8 +1,7 @@
 # PhpSpreadsheet
 
 [![Build Status](https://github.com/PHPOffice/PhpSpreadsheet/workflows/main/badge.svg)](https://github.com/PHPOffice/PhpSpreadsheet/actions)
-[![Code Quality](https://scrutinizer-ci.com/g/PHPOffice/PhpSpreadsheet/badges/quality-score.png?b=master)](https://scrutinizer-ci.com/g/PHPOffice/PhpSpreadsheet/?branch=master)
-[![Code Coverage](https://scrutinizer-ci.com/g/PHPOffice/PhpSpreadsheet/badges/coverage.png?b=master)](https://scrutinizer-ci.com/g/PHPOffice/PhpSpreadsheet/?branch=master)
+[![Code Coverage](https://coveralls.io/repos/github/PHPOffice/PhpSpreadsheet/badge.svg?branch=master)](https://coveralls.io/github/PHPOffice/PhpSpreadsheet?branch=master)
 [![Total Downloads](https://img.shields.io/packagist/dt/PHPOffice/PhpSpreadsheet)](https://packagist.org/packages/phpoffice/phpspreadsheet)
 [![Latest Stable Version](https://img.shields.io/github/v/release/PHPOffice/PhpSpreadsheet)](https://packagist.org/packages/phpoffice/phpspreadsheet)
 [![License](https://img.shields.io/github/license/PHPOffice/PhpSpreadsheet)](https://packagist.org/packages/phpoffice/phpspreadsheet)
@@ -11,6 +10,17 @@
 PhpSpreadsheet is a library written in pure PHP and offers a set of classes that
 allow you to read and write various spreadsheet file formats such as Excel and LibreOffice Calc.
 
+This branch (release390) is maintained (for security and some bug fixes), but it is *not* the latest version of PhpSpreadsheet, and may therefore lack features and bug fixes found in the latest version.
+
+## PHP Version Support
+
+LTS: For maintained branches, support for PHP versions will only be maintained for a period of six months beyond the
+[end of life](https://www.php.net/supported-versions) of that PHP version.
+
+Currently the required PHP minimum version is PHP __8.1__, and we [will support that version](https://www.php.net/supported-versions.php) until 30th June 2026.
+
+See the `composer.json` for other requirements.
+
 ## Installation
 
 See the [install instructions](https://phpspreadsheet.readthedocs.io/en/latest/#installation).

diff --git a/infra/LocaleGenerator.php b/infra/LocaleGenerator.php
@@ -5,6 +5,7 @@
 use Exception;
 use PhpOffice\PhpSpreadsheet\Cell\Cell;
 use PhpOffice\PhpSpreadsheet\IOFactory;
+use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
 use PhpOffice\PhpSpreadsheet\Worksheet\Column;
 use PhpOffice\PhpSpreadsheet\Worksheet\Row;
@@ -276,7 +277,7 @@ protected function mapLanguageColumns(Worksheet $translationWorksheet): array
         $this->log("Mapping Languages for {$sheetName}:");
 
         $baseColumn = self::ENGLISH_REFERENCE_COLUMN;
-        $languagesList = $translationWorksheet->getColumnIterator(++$baseColumn);
+        $languagesList = $translationWorksheet->getColumnIterator(StringHelper::stringIncrement($baseColumn));
 
         $languageNameMap = [];
         foreach ($languagesList as $languageColumn) {

diff --git a/samples/Basic1/13_Calculation.php b/samples/Basic1/13_Calculation.php
@@ -1,6 +1,7 @@
 <?php
 
 use PhpOffice\PhpSpreadsheet\Calculation\Calculation;
+use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
 
 mt_srand(1234567890);
@@ -155,7 +156,7 @@
 
 // Calculated data
 $helper->log('Calculated data');
-for ($col = 'B'; $col != 'G'; ++$col) {
+for ($col = 'B'; $col != 'G'; StringHelper::stringIncrement($col)) {
     for ($row = 14; $row <= 41; ++$row) {
         $formula = $spreadsheet->getActiveSheet()->getCell($col . $row)->getValue();
         if (

diff --git a/samples/Basic1/13_CalculationCyclicFormulae.php b/samples/Basic1/13_CalculationCyclicFormulae.php
@@ -1,6 +1,7 @@
 <?php
 
 use PhpOffice\PhpSpreadsheet\Calculation\Calculation;
+use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
 
 require __DIR__ . '/../Header.php';
@@ -21,7 +22,7 @@
 // Calculated data
 $helper->log('Calculated data');
 for ($row = 1; $row <= 2; ++$row) {
-    for ($col = 'A'; $col != 'C'; ++$col) {
+    for ($col = 'A'; $col != 'C'; StringHelper::stringIncrement($col)) {
         $formula = $spreadsheet->getActiveSheet()->getCell($col . $row)->getValue();
         if (
             is_string($formula)

diff --git a/samples/Basic3/39_Dropdown.php b/samples/Basic3/39_Dropdown.php
@@ -2,6 +2,7 @@
 
 use PhpOffice\PhpSpreadsheet\Cell\DataValidation;
 use PhpOffice\PhpSpreadsheet\NamedRange;
+use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
 
 require __DIR__ . '/../Header.php';
@@ -57,7 +58,7 @@ function transpose(string $value): array
     $spreadsheet->getActiveSheet()
         ->setCellValue($continentColumn . ($key + 1), $continent);
 
-    ++$column;
+    StringHelper::stringIncrement($column);
 }
 
 // Hide the dropdown data

diff --git a/samples/ConditionalFormatting/05_Date_Comparisons.php b/samples/ConditionalFormatting/05_Date_Comparisons.php
@@ -1,5 +1,6 @@
 <?php
 
+use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
 use PhpOffice\PhpSpreadsheet\Style\Alignment;
 use PhpOffice\PhpSpreadsheet\Style\Color;
@@ -96,7 +97,7 @@
     ->fromArray($dateFunctionArray, null, 'B1', true);
 $spreadsheet->getActiveSheet()
     ->fromArray($dateTitleArray, null, 'A2', true);
-for ($column = 'B'; $column !== 'L'; ++$column) {
+for ($column = 'B'; $column !== 'L'; StringHelper::stringIncrement($column)) {
     $spreadsheet->getActiveSheet()
         ->fromArray($dataArray, null, "{$column}2", true);
 }
@@ -116,7 +117,7 @@
 
 // Set conditional formatting rules and styles
 $helper->log('Define conditional formatting and set styles');
-for ($column = 'B'; $column !== 'L'; ++$column) {
+for ($column = 'B'; $column !== 'L'; StringHelper::stringIncrement($column)) {
     $wizardFactory = new Wizard("{$column}2:{$column}19");
     /** @var Wizard\DateValue $dateWizard */
     $dateWizard = $wizardFactory->newRule(Wizard::DATES_OCCURRING);
@@ -139,7 +140,7 @@
 $helper->log('Set some additional styling for date formats');
 
 $spreadsheet->getActiveSheet()->getStyle('B:B')->getNumberFormat()->setFormatCode('ddd dd-mmm-yyyy');
-for ($column = 'A'; $column !== 'L'; ++$column) {
+for ($column = 'A'; $column !== 'L'; StringHelper::stringIncrement($column)) {
     if ($column !== 'A') {
         $spreadsheet->getActiveSheet()->getStyle("{$column}:{$column}")
             ->getNumberFormat()->setFormatCode('ddd dd-mmm-yyyy');

diff --git a/samples/LookupRef/VLOOKUP.php b/samples/LookupRef/VLOOKUP.php
@@ -1,5 +1,6 @@
 <?php
 
+use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
 
 require __DIR__ . '/../Header.php';
@@ -40,7 +41,7 @@
 $worksheet->getCell('I5')->setValue('=VLOOKUP(I3, B3:E9, 4, FALSE)');
 $worksheet->getCell('J5')->setValue('=VLOOKUP(J3, B3:E9, 4, FALSE)');
 
-for ($column = 'H'; $column !== 'K'; ++$column) {
+for ($column = 'H'; $column !== 'K'; StringHelper::stringIncrement($column)) {
     for ($row = 4; $row <= 5; ++$row) {
         $cell = $worksheet->getCell("{$column}{$row}");
         $helper->log("{$column}{$row}: " . $cell->getValue() . ' => ' . $cell->getCalculatedValue());

diff --git a/src/PhpSpreadsheet/Calculation/Engine/Operands/StructuredReference.php b/src/PhpSpreadsheet/Calculation/Engine/Operands/StructuredReference.php
@@ -6,6 +6,7 @@
 use PhpOffice\PhpSpreadsheet\Calculation\Exception;
 use PhpOffice\PhpSpreadsheet\Cell\Cell;
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
+use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 use PhpOffice\PhpSpreadsheet\Worksheet\Table;
 use Stringable;
 
@@ -177,8 +178,8 @@ private function getColumns(Cell $cell, array $tableRange): array
         $cellReference = $cell->getCoordinate();
 
         $columns = [];
-        $lastColumn = ++$tableRange[1][0];
-        for ($column = $tableRange[0][0]; $column !== $lastColumn; ++$column) {
+        $lastColumn = StringHelper::stringIncrement($tableRange[1][0]);
+        for ($column = $tableRange[0][0]; $column !== $lastColumn; StringHelper::stringIncrement($column)) {
             $columns[$column] = $worksheet
                 ->getCell($column . ($this->headersRow ?? ($this->firstDataRow - 1)))
                 ->getCalculatedValue();

diff --git a/src/PhpSpreadsheet/Cell/Cell.php b/src/PhpSpreadsheet/Cell/Cell.php
@@ -466,7 +466,7 @@ public function getCalculatedValue(bool $resetLog = true): mixed
                                         }
                                     }
                                 }
-                                ++$newColumn;
+                                StringHelper::stringIncrement($newColumn);
                             }
                             ++$newRow;
                         } else {
@@ -478,7 +478,7 @@ public function getCalculatedValue(bool $resetLog = true): mixed
                                     }
                                 }
                             }
-                            ++$newColumn;
+                            StringHelper::stringIncrement($newColumn);
                         }
                         if ($spill) {
                             break;
@@ -501,10 +501,10 @@ public function getCalculatedValue(bool $resetLog = true): mixed
                                     $minRow = (int) $matches[2];
                                     // https://github.com/phpstan/phpstan/issues/11602
                                     $maxCol = $matches[4]; // @phpstan-ignore-line
-                                    ++$maxCol;
+                                    StringHelper::stringIncrement($maxCol);
                                     $maxRow = (int) $matches[5]; // @phpstan-ignore-line
                                     for ($row = $minRow; $row <= $maxRow; ++$row) {
-                                        for ($col = $minCol; $col !== $maxCol; ++$col) {
+                                        for ($col = $minCol; $col !== $maxCol; StringHelper::stringIncrement($col)) {
                                             if ("$col$row" !== $coordinate) {
                                                 $thisworksheet->getCell("$col$row")->setValue(null);
                                             }
@@ -529,14 +529,14 @@ public function getCalculatedValue(bool $resetLog = true): mixed
                                 if ($row !== $newRow || $column !== $newColumn) {
                                     $thisworksheet->getCell($newColumn . $newRow)->setValue($resultValue);
                                 }
-                                ++$newColumn;
+                                StringHelper::stringIncrement($newColumn);
                             }
                             ++$newRow;
                         } else {
                             if ($row !== $newRow || $column !== $newColumn) {
                                 $thisworksheet->getCell($newColumn . $newRow)->setValue($resultRow);
                             }
-                            ++$newColumn;
+                            StringHelper::stringIncrement($newColumn);
                         }
                     }
                     $thisworksheet->getCell($column . $row);

diff --git a/src/PhpSpreadsheet/Reader/Csv.php b/src/PhpSpreadsheet/Reader/Csv.php
@@ -452,7 +452,7 @@ private function loadStringOrFile2(string $filename, Spreadsheet $spreadsheet, b
                     // Set cell value
                     $sheet->getCell($columnLetter . $outRow)->setValue($rowDatum);
                 }
-                ++$columnLetter;
+                StringHelper::stringIncrement($columnLetter);
             }
             $rowData = self::getCsv($fileHandle, 0, $delimiter, $this->enclosure, $this->escapeCharacter);
             ++$currentRow;

diff --git a/src/PhpSpreadsheet/Reader/Html.php b/src/PhpSpreadsheet/Reader/Html.php
@@ -16,6 +16,7 @@
 use PhpOffice\PhpSpreadsheet\Helper\Dimension as CssDimension;
 use PhpOffice\PhpSpreadsheet\Helper\Html as HelperHtml;
 use PhpOffice\PhpSpreadsheet\Reader\Security\XmlScanner;
+use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
 use PhpOffice\PhpSpreadsheet\Style\Border;
 use PhpOffice\PhpSpreadsheet\Style\Color;
@@ -525,7 +526,7 @@ private function processDomElementTable(Worksheet $sheet, int &$row, string &$co
             $this->processDomElement($child, $sheet, $row, $column, $cellContent);
             $column = $this->releaseTableStartColumn();
             if ($this->tableLevel > 1) {
-                ++$column;
+                StringHelper::stringIncrement($column);
             } else {
                 ++$row;
             }
@@ -538,7 +539,7 @@ private function processDomElementTr(Worksheet $sheet, int &$row, string &$colum
     {
         if ($child->nodeName === 'col') {
             $this->applyInlineStyle($sheet, -1, $this->currentColumn, $attributeArray);
-            ++$this->currentColumn;
+            StringHelper::stringIncrement($this->currentColumn);
         } elseif ($child->nodeName === 'tr') {
             $column = $this->getTableStartColumn();
             $cellContent = '';
@@ -615,7 +616,7 @@ private function processDomElementDataFormat(Worksheet $sheet, int $row, string
     private function processDomElementThTd(Worksheet $sheet, int &$row, string &$column, string &$cellContent, DOMElement $child, array &$attributeArray): void
     {
         while (isset($this->rowspan[$column . $row])) {
-            ++$column;
+            StringHelper::stringIncrement($column);
         }
         $this->processDomElement($child, $sheet, $row, $column, $cellContent);
 
@@ -635,7 +636,7 @@ private function processDomElementThTd(Worksheet $sheet, int &$row, string &$col
             //create merging rowspan and colspan
             $columnTo = $column;
             for ($i = 0; $i < (int) $attributeArray['colspan'] - 1; ++$i) {
-                ++$columnTo;
+                StringHelper::stringIncrement($columnTo);
             }
             $range = $column . $row . ':' . $columnTo . ($row + (int) $attributeArray['rowspan'] - 1);
             foreach (Coordinate::extractAllCellReferencesInRange($range) as $value) {
@@ -654,13 +655,13 @@ private function processDomElementThTd(Worksheet $sheet, int &$row, string &$col
             //create merging colspan
             $columnTo = $column;
             for ($i = 0; $i < (int) $attributeArray['colspan'] - 1; ++$i) {
-                ++$columnTo;
+                StringHelper::stringIncrement($columnTo);
             }
             $sheet->mergeCells($column . $row . ':' . $columnTo . $row);
             $column = $columnTo;
         }
 
-        ++$column;
+        StringHelper::stringIncrement($column);
     }
 
     protected function processDomElement(DOMNode $element, Worksheet $sheet, int &$row, string &$column, string &$cellContent): void
@@ -898,7 +899,7 @@ private function applyInlineStyle(Worksheet &$sheet, int $row, string $column, a
         } elseif (isset($attributeArray['rowspan'], $attributeArray['colspan'])) {
             $columnTo = $column;
             for ($i = 0; $i < (int) $attributeArray['colspan'] - 1; ++$i) {
-                ++$columnTo;
+                StringHelper::stringIncrement($columnTo);
             }
             $range = $column . $row . ':' . $columnTo . ($row + (int) $attributeArray['rowspan'] - 1);
             $cellStyle = $sheet->getStyle($range);
@@ -908,7 +909,7 @@ private function applyInlineStyle(Worksheet &$sheet, int $row, string $column, a
         } elseif (isset($attributeArray['colspan'])) {
             $columnTo = $column;
             for ($i = 0; $i < (int) $attributeArray['colspan'] - 1; ++$i) {
-                ++$columnTo;
+                StringHelper::stringIncrement($columnTo);
             }
             $range = $column . $row . ':' . $columnTo . $row;
             $cellStyle = $sheet->getStyle($range);

diff --git a/src/PhpSpreadsheet/Reader/Ods.php b/src/PhpSpreadsheet/Reader/Ods.php
@@ -19,6 +19,7 @@
 use PhpOffice\PhpSpreadsheet\RichText\RichText;
 use PhpOffice\PhpSpreadsheet\Shared\Date;
 use PhpOffice\PhpSpreadsheet\Shared\File;
+use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
 use PhpOffice\PhpSpreadsheet\Style\NumberFormat;
 use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
@@ -394,7 +395,9 @@ public function loadIntoExisting(string $filename, Spreadsheet $spreadsheet): Sp
                                     $spreadsheet->getActiveSheet()
                                         ->getColumnDimension($tableColumnString)
                                         ->setWidth($columnWidth->toUnit('cm'), 'cm');
-                                    ++$tableColumnString;
+                                    StringHelper::stringIncrement(
+                                        $tableColumnString
+                                    );
                                 }
                             }
                             $tableColumnIndex += $rowRepeats;
@@ -422,7 +425,7 @@ public function loadIntoExisting(string $filename, Spreadsheet $spreadsheet): Sp
                                         }
 
                                         for ($i = 0; $i < $colRepeats; ++$i) {
-                                            ++$columnID;
+                                            StringHelper::stringIncrement($columnID);
                                         }
 
                                         continue;
@@ -448,7 +451,9 @@ public function loadIntoExisting(string $filename, Spreadsheet $spreadsheet): Sp
                                         $lastRow = $rowID + $arrayRow - 1;
                                         $lastCol = $columnID;
                                         while ($arrayCol > 1) {
-                                            ++$lastCol;
+                                            StringHelper::stringIncrement(
+                                                $lastCol
+                                            );
                                             --$arrayCol;
                                         }
                                         $cellDataRef = "$columnID$rowID:$lastCol$lastRow";
@@ -612,7 +617,9 @@ public function loadIntoExisting(string $filename, Spreadsheet $spreadsheet): Sp
                                 if ($type !== null) {
                                     for ($i = 0; $i < $colRepeats; ++$i) {
                                         if ($i > 0) {
-                                            ++$columnID;
+                                            StringHelper::stringIncrement(
+                                                $columnID
+                                            );
                                         }
 
                                         if ($type !== DataType::TYPE_NULL) {
@@ -664,7 +671,7 @@ public function loadIntoExisting(string $filename, Spreadsheet $spreadsheet): Sp
                                 // Merged cells
                                 $this->processMergedCells($cellData, $tableNs, $type, $columnID, $rowID, $spreadsheet);
 
-                                ++$columnID;
+                                StringHelper::stringIncrement($columnID);
                             }
                             $rowID += $rowRepeats;
 

diff --git a/src/PhpSpreadsheet/Reader/Slk.php b/src/PhpSpreadsheet/Reader/Slk.php
@@ -407,7 +407,11 @@ private function addWidth(Spreadsheet $spreadsheet, string $columnWidth, string
                 $endCol = Coordinate::stringFromColumnIndex((int) $endCol);
                 $spreadsheet->getActiveSheet()->getColumnDimension($startCol)->setWidth((float) $columnWidth);
                 do {
-                    $spreadsheet->getActiveSheet()->getColumnDimension((string) ++$startCol)->setWidth((float) $columnWidth);
+                    $spreadsheet->getActiveSheet()
+                        ->getColumnDimension(
+                            StringHelper::stringIncrement($startCol)
+                        )
+                        ->setWidth((float) $columnWidth);
                 } while ($startCol !== $endCol);
             }
         }

diff --git a/src/PhpSpreadsheet/Reader/Xls.php b/src/PhpSpreadsheet/Reader/Xls.php
@@ -3486,9 +3486,9 @@ private function includeCellRangeFiltered(string $cellRangeAddress): bool
         if ($this->getReadFilter() !== null) {
             $includeCellRange = false;
             $rangeBoundaries = Coordinate::getRangeBoundaries($cellRangeAddress);
-            ++$rangeBoundaries[1][0];
+            StringHelper::stringIncrement($rangeBoundaries[1][0]);
             for ($row = $rangeBoundaries[0][1]; $row <= $rangeBoundaries[1][1]; ++$row) {
-                for ($column = $rangeBoundaries[0][0]; $column != $rangeBoundaries[1][0]; ++$column) {
+                for ($column = $rangeBoundaries[0][0]; $column != $rangeBoundaries[1][0]; StringHelper::stringIncrement($column)) {
                     if ($this->getReadFilter()->readCell($column, $row, $this->phpSheet->getTitle())) {
                         $includeCellRange = true;