MATLAB: Accessing the string elements

indexingMATLABstring

I have 3 strings like the following:
world=["America", "Europe"]; % Parent String 
America=["USA", "Brazil", "Argentina"]; % Child1 String 
Europe=["France", "Germany", "England"]; % Child2 String
I want to access the elements of the child string (Country names) from the Parent string(world) and use it inside a for loop for further operation. I am trying in the following way:
for i=1:2
  d=world(i); % Temporary variable to store the continent name
for j=1:3
disp(d(j)); % Throws an Error: "Index exceeds Matrix dimensions
end
end
What am I doing wrong? Any help will be highly appreciated.

Best Answer

Here is one way, as string arrays are "iterable".
continents = ["America", "Europe"] ; 
countries.America = ["USA", "Brazil", "Argentina"] ;
countries.Europe  = ["France", "Germany", "England"] ;
for continent = continents
    fprintf('%s :\n', continent ) ;
    for country = countries.(continent)
        fprintf('\t%s\n', country) ;
    end
end
Yet, using dynamic field names for that is usually not advised. You could use cell arrays instead:
continents = {"America", "Europe"} ; 
countries{1} = {"USA", "Brazil", "Argentina"} ;
countries{2} = {"France", "Germany", "England"} ;
for continentId = 1 : numel( continents )
    fprintf('%s :\n', continents{continentId} ) ;
    for countryId = 1 : numel( countries{continentId} )
        fprintf('\t%s\n', countries{continentId}{countryId} ) ;
    end
end
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