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# multidimensional areays

i dont really understand the concept and i really passed the quiz randomly, are them important, can someone explain better em?

6/22/2016 10:45:51 PM

Guillermo

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Single dimension arrays are used to store a objects of same type. For eg: To store employees record or students record. Assume the case if you want to store students/employees informations from various departments. So multidimensional array comes in the picture. For eg: Info _info [10][20]; Here first dimension (10) represents the number of department and second dimension (20) represents number of students in that particular department. _info [0] pointing to the first department students information. _info [2][3] pointing to the third department and 4 student information. Hope this helps you to understand and usage for multidimensional Array.

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Sorry I am not sure what exactly your question is. But, if you want to intialize the 2d array, you can achieve like this info[][] = {{dept1stu1, dept1stu2,....}, {dept2stu1, dept2stu2,...}, {.....}, {.....}, ....... }; info[1][0] is pointing to dept2stu2. Hope it's helpful and addressed your doubt

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There are better methods for storing that information. For instance, using the Map collection, you can define a set of "keys" corresponding to the departments, and for each key, define an array representing students. Map<String, String[]> deptRoll = new HashMap<String, String[]>(); deptRoll.put("dept1", {"stud1", "stud2", ...}); deptRoll.put("dept2", {"stud3", "stud4", ...}); System.out.println(deptRoll.get("dept1")[0]); Output: "stud1"

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For two-dimensional arrays you can picture a matrix: String [][] students = { {"stud1", "stud2", "stud3"}, {"stud4", "stud5", "stud6"}, {"stud7", "stud8", "stud9"} } Array indices start with 0, so to reference an element at a given row-col position, you use arrayName[row - 1][col - 1]. For "stud6" in row 2, col 3, we write: students[2 - 1][3 - 1] which is students[1][2] which will return "stud6" Higher-order arrays are also possible but harder to visualize, and often they are replaced by other structures better suited to multidimensional data.

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wow really thanks i was thinking about matrix but didnt realize how to do it, thanks!

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As Yellephant said there is hell lot of ways to store these dept student informations. But this question is related to multidimensional array I shown this example use array.

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int a[3][2][4][5]; the [3][2] is a 3x2 table. the [4] makes them 4 tables, each is 3x2. the [5] makes it 5 sets .. each set has 4 tables, each table is 3x2.

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Thanks! but when u define a multidimensional array in code its like info[][] ={dep1, dep2} {student 1... or how u could express the students in each departament?

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its good but i dont understand how the syntax exactly work