Struct Operations
====================

struct
------

**Syntax** ::

  s = struct
  s = struct(fieldname1,value1,…,fieldnameN,valueN)
  s = struct([])

**Description**

This operation returns struct arras with the specified fields and values.

 - The form ``struct`` returns a 1 by 1 struct array with no fields.
 - The form ``struct(fieldname1,value1,…,fieldnameN,valueN)`` returns a struct
   array with the given field and values.  If any of the field or values provided
   or non-scalar, then the dimensions of all the non-scalar field and values should
   be the same, and the array returned will have the non-scalar dimension.
 - The form ``struct([])`` returns a 0 by 0 empty struct array with no fields.

fieldnames
----------

**Syntax** ::

  fieldnames(s)

**Description**

Given a struct or struct array, this returns the names of the fields as a cell array.


isfield
-------------

**Syntax** ::

      tf = isfield(S, 'field')
      tf = isfield(S, C)


This function determines if a structure array contains the given field
name(s).

- The first form takes a single field name and returns a
  scalar logical value which is true if the structure array contains
  the given field name, and false otherwise.
- The second form accepts a structure array and a cell array of
  character vectors, each indicating a field name.  The return value
  of the function is a logical array with the same dimensions as the
  cell array, containing a logical value indicating, for each field
  name, if that field is present in the given structure array.



isstruct
-------------

**Syntax** ::

    tf = isstrut(A)


This function determines if a value is a scalar or array of structures.  It
returns a scalar true if so, and false otherwise.


rmfield
-------------

**Syntax** ::

    s = rmfield(s,field)


This function removes the named field or fields from the structure
array ``s`` and returns the modified result.  ``field`` should either
be a single field name, or a cell array of field names.


getfield
-------------

**Syntax** ::

    value = getfield(s, field)


This function extracts the value of the named ``field`` from the
scalar structure ``s``.

MATLAB supports more complicated forms of the ``getfield`` function,
but these forms are not currently supported by Grackle.


setfield
----------------

**Syntax** ::

    s = setfield(s,field,value)


Set the value of ``field`` in scalar structure ``s`` to ``value``,
returning the modified result.  ``field`` should be a character array
denoting a field name.

MATLAB supports more complicated forms of the ``setfield`` function,
but these forms are not currently supported by Grackle.