find the size of a structured array

I have a structured array called 'Data' which is a 1x1 struct, within this structured array are Data.note1, Data.note2, Data.note3, Data.note4. How is it possible to find the number of fields in the structured array? Where if it was a cell you would use length(cell)! Doing this for the structured array returns 1 where it should be 4.

[Stephen23]

"Doing this for the structured array returns 1 where it should be 4."

No, it should return 1 because you have a scalar structure, you even wrote this yourself: "I have a structured array called 'Data' which is a 1x1 struct". A 1x1 array is scalar, i.e. has only one element, regardless of its class:

https://www.mathworks.com/help/matlab/matlab_prog/fundamental-matlab-classes.html

In contrast a structure array with four elements has ... four elements:

S = struct('X',{1,2,3,4}) % 1x4, not 1x1

S = 1×4 struct array with fields:
    X

length(S)

ans = 4

The size of a structure array is completely independent of how many fields it has.

https://www.mathworks.com/help/matlab/matlab_prog/create-a-structure-array.html

Answer 1

[Jonathan Sullivan]

length(fieldnames(Data))