Need better way to sum up data

Question

i have this class ``` public class ConnectionResult { private int connectionPercentage; public int ConnectPercentage { get { return connectionPercentage; } } public ConnectionResult(int ip) { // Check connection and set connectionPercentage } } ``` and i have a manager that gets several lists of ConnectionResult and count each value greater then a specific number determined by configuration. my implementation is so: ``` public class CurrentConnections { private static CurrentConnections inst; private CurrentConnections() { } public static CurrentConnections GetInstance { get { if (inst != null) { inst = new CurrentConnections(); } return inst; } } public int CountActiveConnections(params List[] conns) { int rtVal = 0; foreach (List connectionResult in conns) { foreach (var currConn in connectionResult) { if (currConn.ConnectPercentage > ACCEPTABLE_CONNECTION) { rtVal++; } } } return rtVal; } } ``` but i want to make it better, so i started to write…

Accepted Answer

John Skeet's answer is excellent, but to address the error that you're seeing, the query would be:

```
conns.Sum(x => x.Count(y => y.ConnectPercentage > ACCEPTABLE_CONNECTION));
```

- `Count` accepts a function which returns `bool` and returns the number of items from the collection which meet that criteria.

- `Sum` accepts a function which returns `int` (among others), and returns the sum of the results of the expression applied to each item.

Of course, whether you select every item from each subset and then count them up (like John Skeet suggests), or you count the items from each subset and then add up the counts (like my code suggests), the result will be exactly the same.

Need better way to sum up data

Solution

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