How to use generic to create common method for addition for multiple data types?

Question

I was supposed to write a method, which will perform addition on collection of integer, float or double. I was going to write a three methods which will traverse three different types perform addition and return the value. It works. I am just curious, Is this can be done in a single method, where the type is passed a a generic type, something like

public static T SUM<T>(IEnumerable<T> dataCollection)
{
T total;
foreach(var value in dataCollection)
total += value;
return total;
}

I was able to resolve it with normal three method implementation but just curious, is it even possible?

Thanks,

JaredPar · Accepted Answer · 2012-03-13 01:42:18Z

6

It's not possible to use operators like + / - / * / etc ... on expressions which are typed to generic type parameters. These only work when dealing with concrete types.

To do this with generics you'll need to pass in an abstraction which understands how to do operations like + on the actual type of T. For example, here's a lambda example

public static T SUM<T>(IEnumerable<T> dataCollection, Func<T, T, T> sum)
{
  T total = default(T);
  foreach(var value in dataCollection)
    total = sum(total, value);
  return total;
}

List<int> list = ...;
list.Sum((left, right) -> left + right);

Note: As several have pointed out the function I wrote here is essentially identical to System.Linq.Enumerable.Aggregate. Please use that vs. putting this in your code.

edited Mar 13, 2012 at 1:42

answered Mar 12, 2012 at 21:40

JaredPar

760k152 gold badges1.3k silver badges1.5k bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

KeithS Over a year ago

Of course, that's little more than a roll-your-own Aggregate() function, as the lambda passed could be anything from left - right to left / right.

Alexei Levenkov Over a year ago

@Nair, note that exactly this function is already there Enumerable.Aggregate, please try to use it instead unless you doing it to learn something.

Nair Over a year ago

Yes it is part of learning experience then again, I did not know about Aggregate as well.

Nair Over a year ago

@JaredPar in the above method as it is, sum(total, value) compiler compains about total not assigned.

Collectives™ on Stack Overflow

How to use generic to create common method for addition for multiple data types?

1 Answer 1

4 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related