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<h4 class="subsection">6.1.3 Creating Structures</h4>

<p>As well as indexing a structure with ".", Octave can create a structure
with the <code>struct</code> command.  <code>struct</code> takes pairs of arguments,
where the first argument in the pair is the fieldname to include in the
structure and the second is a scalar or cell array, representing the
values to include in the structure or structure array.  For example

<pre class="example">     struct ("field1", 1, "field2", 2)
     &rArr; ans =
           {
             field1 =  1
             field2 =  2
           }
</pre>
   <p>If the values passed to <code>struct</code> are a mix of scalar and cell
arrays, then the scalar arguments are expanded to create a
structure array with a consistent dimension.  For example

<pre class="example">     s = struct ("field1", {1, "one"}, "field2", {2, "two"},
             "field3", 3);
     s.field1
          &rArr;
             ans =  1
             ans = one
     
     s.field2
          &rArr;
             ans =  2
             ans = two
     
     s.field3
          &rArr;
             ans =  3
             ans =  3
</pre>
   <p>If you want to create a struct which contains a cell array as an
individual field, you have to put it into another cell array like in
the following example:

<pre class="example">     struct ("field1", {{1, "one"}}, "field2", 2)
          &rArr; ans =
             {
               field1 =
     
             {
               [1,1] =  1
               [1,2] = one
             }
     
               field2 =  2
             }
</pre>
   <!-- ov-struct.cc -->
   <p><a name="doc_002dstruct"></a>

<div class="defun">
&mdash; Built-in Function:  <b>struct</b> (<var>"field", value, "field", value, <small class="dots">...</small></var>)<var><a name="index-struct-373"></a></var><br>
<blockquote>
        <p>Create a structure and initialize its value.

        <p>If the values are cell arrays, create a structure array and initialize
its values.  The dimensions of each cell array of values must match. 
Singleton cells and non-cell values are repeated so that they fill
the entire array.  If the cells are empty, create an empty structure
array with the specified field names.

        <p>If the argument is an object, return the underlying struct. 
</p></blockquote></div>

   <p>The function <code>isstruct</code> can be used to test if an object is a
structure or a structure array.

<!-- ov-struct.cc -->
   <p><a name="doc_002disstruct"></a>

<div class="defun">
&mdash; Built-in Function:  <b>isstruct</b> (<var>expr</var>)<var><a name="index-isstruct-374"></a></var><br>
<blockquote><p>Return 1 if the value of the expression <var>expr</var> is a structure. 
</p></blockquote></div>

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