How to optimize this code

Question

it has a property: string Code and 10 other.

common codes is list of strings(string[] ) cars a list of cars(Car[]) filteredListOfCars is List.

for (int index = 0; index < cars.Length; index++)
{
    Car car = cars[index];
    if (commonCodes.Contains(car.Code))
    {
         filteredListOfCars.Add(car);
    }
}

Unfortunately this piece of methodexecutes too long.

I have about 50k records

How can I lower execution time??

Answer 1

The easiest optimization isto convert commonCodes from a string[] to a faster lookup structure such as a Dictionary<string,object> or a HashSet<string> if you are using .Net 3.5 or above. This will reduce the big O complexity of this loop and depending on the size of commonCodes should make this loop execute faster.