Get the list of index for a string in an array?
You can do something as follows
string[] cars = { "Volvo", "BMW", "Volvo", "Mazda", "BMW", "BMW" };
// Get indices of BMW
var indicesArray = cars.Select((car, index) => car == "BMW" ? index : -1).Where(i => i != -1).ToArray();
// Display indices
Label1.Text = string.Join(", ", indicesArray);
You can try the following,
string[] cars = {"Volvo", "BMW", "Volvo", "Mazda","BMW","BMW"};
//returns **{1,4,5}** as a list
var res = Enumerable.Range(0, cars.Length).Where(i => cars[i] == "BMW").ToList();
//joined items of list as 1,4,5
Label1.Text = string.Join(",", res);
Previous answers are also ok. But I would do it like this if you need to do a lot of similar index searches. Will reduce the amount of code you write in the long term.
public static class SequenceExt
{
public static IEnumerable<int> FindIndexes<T>(this IEnumerable<T> items, Func<T, bool> predicate)
{
int index = 0;
foreach (T item in items)
{
if (predicate(item))
{
yield return index;
}
index++;
}
}
}
use it like this:
string[] cars = { "Volvo", "BMW", "Volvo", "Mazda", "BMW", "BMW" };
var indexes = cars.FindIndexes(s => s.Equals("BMW")).ToArray();
returns 1,4,5