c# array select

I have a bool array

a[1] = true
a[2] = false
a[3] = true
a[4] = true

how do i select only true values to a ne开发者_如何学Pythonw array?

Thanks!

I don't really know why you would want to do this but...

bool[] a = {true, false, true, true};
bool[] b = a.Where(x => x).ToArray();

If you just want to count how many "true"s there are:

int c = a.Count(x => x);

If you mean a new array containing the indices of 'a' that had a value of true...

// Assuming here that a begins at 0, unlike your example...
Enumerable.Range(0, a.Length).Where(i=>a[i]).ToArray();

bool[] result = a.Where(x => x).ToArray();