#1,167 – Passing a Lambda Expression to a Method

You can use a lambda expression anywhere that a delegate instance is expected.  This includes passing a lambda expression as a parameter to a method that takes a delegate type.

In the example below, we have a method that has two parameters that are delegate types.  It takes a transformer function that accepts and int and returns an int.  It also accepts a delegate that reports something about two different int values.

            // Transform one int to another int and report the result
            static void TransformAndReport(Func<int,int> transformer, Action<int,int> reporter, int[] data)
            {
                foreach (int ival in data)
                {
                    int newVal = transformer(ival);
                    reporter(ival, newVal);
                }
            }

We can call this method by passing in two different lambda expressions.

            TransformAndReport(
                (i) => i * 3,
                (inVal,outVal) => Console.WriteLine("{0} became {1}", inVal, outVal),
                new int[]{1, 2, 3});

            TransformAndReport(
                (i) => {
                    double cosVal = Math.Cos(i);
                    return (int)Math.Truncate((cosVal * 100) - i);
                },
                (inVal, outVal) => Console.WriteLine("{0} yields {1}", inVal, outVal),
                new int[] { 20, 40, 60, 90 });

1167-001

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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.

One Response to #1,167 – Passing a Lambda Expression to a Method

  1. Pingback: Dew Drop – August 25, 2014 (#1841) | Morning Dew

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