need help with dynamic field expression

The assignment is that we are given a structure with two unknown fields, one is a cell array inside of which is stored a string, the other is not a cell array. The function fixArray should keep the field with the cell in it (don't do anything to it) but remove the other field that is not a cell array. Then, replace the removed field with a new field that is named as the string inside the cell array. To the new field, the string "it's working!" should be assigned. Output the final structure.

I was trying to use dynamic field expression when creating the new structure but it doesn't seem to be working. please help!!!

 function[new_structure] = fixArray(old_structure)

 flds= fieldnames(old_structure);

 a= old_structure.(flds{1});

 b= old_structure.(flds{2});

 A= iscell(a);

 B= iscell(b);

 new_structure = struct;

 if A==1

      new_structure = struct(flds{1}, a);

      new_structure = rmfield(old_structure, flds{2});

      new_structure = struct(a, 'It works!');

 end

 if A==0

     new_structure = struct(flds{2}, b);

     new_structure = rmfield(old_structure, flds{1});

     new_structure = struct(a, 'It works!');

 end

 end

Answer 1

[Walter Roberson]

Your code has

      new_structure = struct(flds{1}, a);

      new_structure = rmfield(old_structure, flds{2});

      new_structure = struct(a, 'It works!');

which creates new_structure and then twice overwrites it with a completely different value. The effect is as if you had only executed the last of those three lines.

[Kelly]

Okay I see that now. If I try to do

 new_structure.(a) = 'It works!';

I get an error that says: Argument to dynamic structure reference must evaluate to a valid field name.

The variable (a) is a string though, so I am not sure how to create the new field if I don't know what that field needs to be named until the function is called

[Walter Roberson]

If A==1 then iscell(a) is true, and you would be trying to use the cell array a instead of the string stored in the cell array. a{1} to get to the content of the first element of a.

[Kelly]

Awesome, I got it! Thank you!