#### 6.1.2 Structure Arrays ¶

A structure array is a particular instance of a structure, where each of the fields of the structure is represented by a cell array. Each of these cell arrays has the same dimensions. Conceptually, a structure array can also be seen as an array of structures with identical fields. An example of the creation of a structure array is

    x(1).a = "string1";
    x(2).a = "string2";
    x(1).b = 1;
    x(2).b = 2;

which creates a 1-by-2 structure array with two fields. Another way to create a structure array is with the `struct` function (see Creating Structures). As previously, to print the value of the structure array, you can type its name:

    x
         ⇒  x =
            {
              1x2 struct array containing the fields:

                a
                b
            }

Individual elements of the structure array can be returned by indexing the variable like `x(1)`, which returns a structure with two fields:

    x(1)
         ⇒  ans =
            {
              a = string1
              b =  1
            }

Furthermore, the structure array can return a comma-separated list of field values (see Comma-Separated Lists), if indexed by one of its own field names. For example:

    x.a
         ⇒
            ans = string1
            ans = string2

Here is another example, using this comma-separated list on the left-hand side of an assignment:

    [x.a] = deal ("new string1", "new string2");
     x(1).a
         ⇒  ans = new string1
     x(2).a
         ⇒  ans = new string2

Just as for numerical arrays, it is possible to use vectors as indices (see Index Expressions):

    x(3:4) = x(1:2);
    [x([1,3]).a] = deal ("other string1", "other string2");
    x.a
         ⇒
            ans = other string1
            ans = new string2
            ans = other string2
            ans = new string2

The function `size` will return the size of the structure. For the example above

    size (x)
         ⇒  ans =

              1   4

Elements can be deleted from a structure array in a similar manner to a numerical array, by assigning the elements to an empty matrix. For example

    in = struct ("call1", {x, Inf, "last"},
                 "call2", {x, Inf, "first"})
         ⇒  in =
            {
              1x3 struct array containing the fields:

                call1
                call2
            }

    in(1) = [];
    in.call1
         ⇒
           ans = Inf
           ans = last