Accessing Fields in Structs

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MiauMiau
MiauMiau on 14 Mar 2014
Commented: MiauMiau on 14 Mar 2014
Hi
I have a more theoretical question to struct arrays in Matlab. Given I have two structures a and b, defined as follows:
a = struct('b', 0, 'c', 'test')
a(2).b = 5
b = struct('b', {0,5}, 'c', {'test'})
WHY is it now that if I use a(2) the answer is simply
b: 5
c: []
i.e. the second element of c is shown as empty, whereas when I use b(2) the answer is
b: 5
c: 'test'
i.e. the first element of c is repeated as its second element, too?

Accepted Answer

Walter Roberson
Walter Roberson on 14 Mar 2014
Look at the documentation for struct():
If any of the value inputs are nonscalar cell arrays, then s has the same dimensions as the nonscalar cell arrays. For any value that is a scalar cell array or an array of any other data type, struct inserts the contents of value in the relevant field for all elements of s.
Notice the second sentence there. {'test'} is a scalar cell array so it gets copied to all elements of the output.
  1 Comment
MiauMiau
MiauMiau on 14 Mar 2014
Thanks, well that was a bit cryptic before :) But still one question: 'test' is obviously a string - so why is it then called a scalar cell array (and not a nonscalar cell array)?

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