I have a string array that contains... well, strings, some of which are numbers. I am looking to sum only the numbers from the string, using LINQ.
I came up with this:
var array = new string[] { "asd", "asd", "53", null, "51", "asd" };
int sum = array.Where(x => int.TryParse(x, out _)).Select(x => int.Parse(x)).Sum();
However I am wondering if there is a way to, sort of, unite the Where and Select clauses somehow?
Thanks!
You can not combine Where and Select, but you can change it to parse string only once
var sum = array
.Select(text => (IsNumber: int.TryParse(text, out var number), Number: number))
.Where(value => value.IsNumber)
.Sum(value => value.Number);
Another approach to do everything in the Sum
var sum = array.Sum(text => int.TryParse(text, out var number) ? number : 0);
Actually you can unite the Where and Select clauses, only because you calculating a sum.
For text, which is not valid number return 0.
var sum = array
.Select(text => { int.TryParse(text, out var number); return number; })
.Sum();
You can go further and create an extension method for string. Which will make such expressions simpler
public static int ParseOrDefault(string value)
{
int.TryParse(text, out var number);
return number;
}
var sum = array.Sum(value => value.ParseOrDefault());
In this particular case you can use Aggregate:
array.Aggregate(0, (acc, s) => int.TryParse(s, out var val) ? acc + val : acc)
