Octave Programming Tutorial/Struct Arrays

A structure in Octave groups different data types called fields in a single object. Fields are accessed by their names. Declaring a structure A structure is declared by assigning values to its fields. A period (.) separates the name of the field and the name of the structure: >> city.name = 'Liege'; >> city.country = 'Belgium'; >> city.longitude = 50.6333; >> city.latitude = 5.5666; The fields of a structure and their value can by displayed by simply entering the name of the struct: >> city city = { name = Liege country = Belgium longitude = 50.633 latitude = 5.5666 } Manipulating structures A structure can be copied as any objects: >> city_copy = city; In most circumstance, the fields of a structure can be manipulated with the period operator. The value of a field can be overwritten by: >> city.name = 'Outremeuse'; In the same way, the value of a field can be retrieved by: >> city.name ans = Outremeuse The function isstruct can be used to test if object is a structure or not. With the function fieldnames all field names are returned as a cell array: >> fieldnames(city) ans = { [1,1] = name [2,1] = country [3,1] = longitude [4,1] = latitude } To test if a structure contains the a given field named, the function isfield can be used: >> isfield(city,'name') ans = 1 The value of a field can be extract with getfield: >> getfield(city,'name') ans = Liege In a similar way, the value of a field can be set with setfield: >> setfield(city,'name','Outremeuse') The functions isfield, getfield and setfield are useful when the names of a structure are determined during execution of the program.