are c sharp and d flat major the same scale

Before that, other systems of intonation were used, going back to 'just intonation'- pretty much what Pythagoras described over 2000 years ago. Without giving the whole history, equal temperament made it possible to tune a piano, harpsichord, organ or any instrument with one compromised set of intervals so one could play in any key without retuning. Nowadays most of us use equal temperament tuning in which C# and D flat are the same tone. Yes and no, depending on your system of tuning. 'Listen, listen, listen and play, play, play.' (Murphy Henry) Here is my point - for Db you can use the alphabet (and for me my fingers ) and for C# you can't - (all of this excludes the accidentals). In the case of C# - you don't get that alphabet from the C# but rather you have to skip E and go to F: C#.C.D.F.G.A.B.C (again I am leaving off the flats and or sharps). this does not tell you the flats or sharps but it works straight through for the alphabet letters.

I am thinking simple stuff here - alphabet stuff for the key of Db.D.E.F.G.A.B.C.D. This may be faulty thinking on my part - but for the two keys mentioned - Db and C# - if I find a song in that 'tone' I usually call it Db and here is my reasoning: for Db and thinking of the letter names of scales - Db lets me name each letter of the alphabet (you still have to figure / know /adjust for the flats and or sharps).

Thank you Sherry and Diva! That all makes a lot of sense.

Are c sharp and d flat major the same scale