Invalid types 'int[int]' for array subscript error in my Arduino code

[J-M-L]

Don’t post snippets (Snippets R Us!)

Show us how you declared the notes and duration arrays (and the rest of the code and the full compiler error as it will point you at the infringing line)

You also might want to think about the variables naming in this line

int noteDuration = 1000 / noteDuration [thisNote];