Brackets for structure arrays in MATLAB

Structure array is a common type of data used in MATLAB. To deal with it, brackets are used extensively. However, when to use the correct brackets- ( ) and [ ]? Sometimes this can be confusing. Here is a summary about them.

Suppose we have structure arrays
a.b =[1 2; 3 4]
and
c(1).b =[1 2], c(2).b =[3 4].

>> a.b= [1 2; 3 4]
a =
b: [2x2 double]
>> c(1).b =[1 2]
c =
b: [1 2]
>> c(2).b =[3 4]
c =
1x2 struct array with fields:
b

Now, let's try ( ) on both of them.

>> (a.b)
ans =
1 2
3 4
>> (c.b)
ans =
1 2
ans =
3 4

and [ ]

>> [a.b]
ans =
1 2
3 4
>> [c.b]
ans =
1 2 3 4

Through the example, it is easy to see the difference. If we also have d ='more', what will happen if we type c(1).(d) =1?

>> c(1).(d) =1
c =
1x2 struct array with fields:
b
more

Thus ( ) can be used to create dynamic field names. So far, { } haven't been mentioned because this pair of curly braces are mostly for cells.