I didn't even realize HashTable was still being included after all these years since generics were supported in .NET 2, back in 2006. I just now saw that it's carried forward into .NET 5 and 6-Preview as well. HashTable was pretty much replaced by Dictionary once generics were released. At the very least, it's not recommended for new development. I assume it's still around only for really old legacy code. https://docs.microsoft.com/en-us/dotnet/api/system.collections.hashtable?view=net-5.0#remarks https://github.com/dotnet/platform-compat/blob/master/docs/DE0006.md That said, if you still want a list of differences, this link might help: https://www.c-sharpcorner.com/blogs/difference-between-dictionary-and-hashtable-in-c-sharp

Your third attempt is correct - but what is happening to guess_row before/after this code? For example, consider the following:

a = "Hello"
try:
    a = int(input("Enter a number: "))
except ValueError:
    print("Not an integer value...")
print(str(a))

If you enter a valid number, the final line will print out the value you entered. If not, an exception will be raised (showing the error message in the except block) and a will remain unchanged, so the final line will print "Hello" instead.

You can refine this so that an invalid number will prompt the user to re-enter the value:

a = None
while a is None:
    try:
        a = int(input("Enter a number: "))
    except ValueError:
        print("Not an integer value...")
print(str(a))