The following example of returning by reference is from What’s New in C# 7.0:
public ref int Find(int number, int[] numbers)
{
for (int i = 0; i < numbers.Length; i++)
{
if (numbers[i] == number)
{
return ref numbers[i]; // return the storage location, not the value
}
}
throw new IndexOutOfRangeException($"{nameof(number)} not found");
}
That compiles without any problems (as you'd expect as it's copied from the Microsoft blog).
I've written this one:
private static ref int GetReference(string searchTerm)
{
var passwords = new Dictionary<string, int>
{
{"password", 1},
{"123456", 2},
{"12345678", 3},
{"1234", 4},
{"qwerty", 5},
{"12345", 6},
{"dragon", 7}
};
return ref passwords[searchTerm];
}
This one doesn't compile though; it gives the following error:
CS8156 An expression cannot be used in this context because it may not be returned by reference
Why does returning from an array work, but returning from a collection doesn't?
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