attribute?.Description是什么意思？

[stevenjin]

以下代码中的 attribute?.Description中那个?是啥意思？

   public static string GetDescription(Enum value, Boolean nameInstead = true) {
            try {
                Type type = value.GetType();
                string name = Enum.GetName(type, value);
                if (name == null) {
                    return null;
                }

                System.Reflection.FieldInfo field = type.GetField(name);
                DescriptionAttribute attribute = System.Attribute.GetCustomAttribute(field, typeof(DescriptionAttribute)) as DescriptionAttribute;

                if (attribute == null && nameInstead == true) {
                    return name;
                }
                return attribute?.Description;
            } catch {
                return string.Empty;
            }
        }

[键盘敲出字]

这是C#6.0的语法糖 Null 条件运算符 ?.

    return attribute?.Description;
    //等效于以下代码
    if (attribute != null){
        return attribute.Description;
    }
    else{
        return null;
    }