System.Text.Base64Encoding.GetMaxByteCount C# (CSharp) Метод

        public override int GetMaxByteCount(int charCount)
        {
            if (charCount < 0)
                throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException(nameof(charCount), SR.Format(SR.ValueMustBeNonNegative)));
            if ((charCount % 4) != 0)
                throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new FormatException(SR.Format(SR.XmlInvalidBase64Length, charCount.ToString(NumberFormatInfo.CurrentInfo))));
            return charCount / 4 * 3;
        }