%% Change Structure Field Value
% Create a structure with fields named 'File' and 'Format'.

S = struct('File',{'myGraph'},'Format',[])

%
% Short-circuit expressions are useful in if statements when you want multiple conditions to be true. The conditions can build on one another in such a way that it only makes sense to evaluate the second expression if the first expression is true.
% Specify an if statement that executes only when S contains an empty field named 'Format'.

if isfield(S,'Format') && isempty(S.Format)
  S.Format = '.png';
end 
S

% The first condition tests if 'Format' is the name of a field in structure S. The second statement then tests whether the Format field is empty. The truth of the second condition depends on the first. The second condition can never be true if the first condition is not true. Since S has an empty field named 'Format', the body statement executes and assigns S.Format the value '.png'.
% Copyright 2012 The MathWorks, Inc.