Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Cell/DefaultValueBinder.php
public static function dataTypeForValue($pValue)
    {
        // Match the value against a few data types
        if ($pValue === null) {
            return DataType::TYPE_NULL;
        } elseif ($pValue === '') {
            return DataType::TYPE_STRING;
        } elseif ($pValue instanceof RichText) {
            return DataType::TYPE_INLINE;
        } elseif ($pValue[0] === '=' && strlen($pValue) > 1) {
            return DataType::TYPE_FORMULA;
        } elseif (is_bool($pValue)) {
            return DataType::TYPE_BOOL;
        } elseif (is_float($pValue) || is_int($pValue)) {
            return DataType::TYPE_NUMERIC;
        } elseif (preg_match('/^[\+\-]?(\d+\\.?\d*|\d*\\.?\d+)([Ee][\-\+]?[0-2]?\d{1,3})?$/', $pValue)) {
            $tValue = ltrim($pValue, '+-');
            if (is_string($pValue) && $tValue[0] === '0' && strlen($tValue) > 1 && $tValue[1] !== '.') {
                return DataType::TYPE_STRING;
            } elseif ((strpos($pValue, '.') === false) && ($pValue > PHP_INT_MAX)) {
                return DataType::TYPE_STRING;
            }

            return DataType::TYPE_NUMERIC;
        } elseif (is_string($pValue)) {
            $errorCodes = DataType::getErrorCodes();
            if (isset($errorCodes[$pValue])) {
                return DataType::TYPE_ERROR;
            }
        }

        return DataType::TYPE_STRING;
    }
public static function dataTypeForValue($pValue)
    {
        // Match the value against a few data types
        if ($pValue === null) {
            return DataType::TYPE_NULL;
        } elseif ($pValue === '') {
            return DataType::TYPE_STRING;
        } elseif ($pValue instanceof RichText) {
            return DataType::TYPE_INLINE;
        } elseif ($pValue[0] === '=' && strlen($pValue) > 1) {
            return DataType::TYPE_FORMULA;
        } elseif (is_bool($pValue)) {
            return DataType::TYPE_BOOL;
        } elseif (is_float($pValue) || is_int($pValue)) {
            return DataType::TYPE_NUMERIC;
        } elseif (preg_match('/^[\+\-]?(\d+\\.?\d*|\d*\\.?\d+)([Ee][\-\+]?[0-2]?\d{1,3})?$/', $pValue)) {
            $tValue = ltrim($pValue, '+-');
            if (is_string($pValue) && $tValue[0] === '0' && strlen($tValue) > 1 && $tValue[1] !== '.') {
                return DataType::TYPE_STRING;
            } elseif ((strpos($pValue, '.') === false) && ($pValue > PHP_INT_MAX)) {
                return DataType::TYPE_STRING;
            }

            return DataType::TYPE_NUMERIC;
        } elseif (is_string($pValue)) {
            $errorCodes = DataType::getErrorCodes();
            if (isset($errorCodes[$pValue])) {
                return DataType::TYPE_ERROR;
            }
        }

        return DataType::TYPE_STRING;
    }
DataType for value.

@param mixed $pValue

@return string