How to access data in structures?

I'm currently learning how to use structures in MATLAB and I'm finding it a little more confusing than cells and other regular arrays. I'm confused on how to call data stored in specific fields of a structure. I understand the format is "nameofstructure"."nameoffield", but I'm struggling with how to get the data I need from the structure without knowing the name of the fields. Say I had a structure with 2 fields, how would I go about getting the infomation from either one without knowing the name of the field? I tried pulling the names of the fields in a function and using them like so

fieldnames = fieldnames(structure)
fieldInedd = fieldnames(2)
informationfromthisfield = structure.fieldIneed

But this doesn't give a field that matlab can recognize and draw data from. Could anyone help?

[Stephen23]

To access the structure fieldname dynamically you need the syntax given here:

https://www.mathworks.com/help/matlab/matlab_prog/generate-field-names-from-variables.html

and to access the contents of the cell array returned by fieldnames you need to use curly braces:

https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-cell-array.html

Answer 1

[Walter Roberson]

fieldnames = fieldnames(structure)
fieldInedd = fieldnames{2}
informationfromthisfield = structure.(fieldIneed)

Notice the () around the field name: it is important. This syntax is "dynamic field names".

This syntax of dot followed by a variable name or expression in () is also used for referencing table variables that are not valid MATLAB variable names.

[Brett Baxter]

Got it, this works for me. Thank you!