Brother downstairs, have you ever used gtp? Gtp has staff notation. He doesn’t know how to read the staff notation and say there are no markings.
Basically, whatever the first note is is in that key
Or the staff chart you have in your gtp follows the guitar notation
This is a basic Music theory questions. The method is as follows:
First look at the key signature. The key signature is the leftmost side of the staff. There will be a number of sharps or flats on the right side of the treble (bass, etc.) clef. Different sharps and flats represent different keys. Specifically:
The key of C has no key signature. That is, there are no rising and falling marks.
One sharp (#F) is in the key of G
Two sharps (#F, #C) are in the key of D
Three sharps ( #F, #C, #G) are in the key of A
Four sharps (#F, #C, #G, #D) are in the key of E
Five sharps (#F, #C, #G, #D, #A) is the key of B
The six sharps (#F, #C, #G, #D, #A, #E) are #F key
The seven sharps (#F, #C, #G, #D, #A, #E, #B) are #C key
See above What patterns can you see in the sharp tone? The last sharp in each key goes up a half step, which is the key represented by all these sharps; the sharp in the next key will add a sharp to the previous key. So as long as you remember the order of all sharps (simplified by simplified notation, it is 4 1 5 2 6 3 7), you can know what key it is.
The flat keys also have rules, as follows:
One flat (bB) is the key of F
Two flats (bB, bE) are the key of bB
Three flats (bB, bE, bA) are in the key of bE
Four flats (bB, bE, bA, bD) are in the key of bA
Five flats (bB, bE, bA, bD, bG) are in the key of bD
Six flats (bB, bE, bA, bD, bG, bC) are in the key of bG
The seven flats (bB, bE, bA, bD, bG, bC, bF) are in the key of bC
First of all, the order of the note names of the flats is exactly the opposite of that of the sharps (7 3 6 2 5 1 4). When there are more than two flats, the penultimate flat is exactly the name of the key.
After understanding the above theory, and then memorizing the order of sharps and flats, just look at You can immediately tell what key it is by seeing how many sharps or flats there are on the score.