#366 – Defining an Indexer with More than One Parameter

An indexer will typically have a single parameter, often based on an integer type.

        public LogMessage this[int i]
            get { return messages[i]; }
            set { messages[i] = value; }

You can also define an indexer that takes more than one parameter.  In the example below, we have an internal data structure that stores a list of messages for each day of the week.  We can retrieve a specific message by passing in a parameter representing the day, as well as a 0-based index into the list of messages for that day.

            // Get 1st Saturday message
            LogMessage msg = log[Days.Sat, 0];

Here’s what the definition of the indexer looks like.

        private Dictionary<Days, List<LogMessage>> dailyMessages = new Dictionary<Days, List<LogMessage>>();

        public LogMessage this[Days day, int i]
            get { return dailyMessages[day][i]; }

About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

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