Question

Class order {
Guid Id;
int qty;
}

Using LINQ expression, how can I verify if the qty is the same for all orders in a list?

Thanks in advance!

Answer 1

You can use GroupBy:

bool allEqual = orders.GroupBy(o => o.qty).Count() == 1;

or, little bit more efficient but less readable:

bool allEqual = !orders.GroupBy(o => o.qty).Skip(1).Any();

or, definitely more efficient using Enumerable.All:

int firstQty = orders.First().qty;  // fyi: throws an exception on an empty sequence
bool allEqual = orders.All(o => o.qty == firstQty);