JuniorTheoryCommon

What does the program print (lines separated by spaces)?

var seen = new HashSet<string>();
seen.Add("cat");
seen.Add("dog");
bool added = seen.Add("cat");
Console.WriteLine(added);
Console.WriteLine(seen.Count);

False 2

Expecting True 2: Add reports whether it added the value, so a repeat returns false while the set stays at two values.
Expecting an exception, as with a dictionary's Add: a set skips a repeat and returns false instead of throwing.

What does seen.Contains("dog") print after the same lines?
How would you use the result of Add to find the first word that repeats in a list?

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JuniorTheoryCommon

What does the program print (lines separated by spaces)?

var seen = new HashSet<string>();
seen.Add("cat");
seen.Add("dog");
bool added = seen.Add("cat");
Console.WriteLine(added);
Console.WriteLine(seen.Count);

False 2

Expecting True 2: Add reports whether it added the value, so a repeat returns false while the set stays at two values.
Expecting an exception, as with a dictionary's Add: a set skips a repeat and returns false instead of throwing.

What does seen.Contains("dog") print after the same lines?
How would you use the result of Add to find the first word that repeats in a list?

Back to questions Open topic in roadmap →Answer it yourself — Quiz