Ch 8 Multidimensional Array in oop as per gtu.pptx

Ch 8 Multidimensional Array in oop as per gtu.pptx

• 1.
  MULTIDIMENSIONAL ARRAYS
• 2.
  2 Two-Dimensional Array Basics Data in a table or a matrix can be represented using a two-dimensional array  element in a two-dimensional array is accessed through a row and column index  syntax for declaring a two-dimensional array  elementType[][] arrayRefVar; or elementType arrayRefVar[][];  int[][] matrix; or int matrix[][];  matrix = new int[5][5];
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  3
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  4 Initialize an array
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  5 Obtaining the Lengthsof Two- Dimensional Arrays  A two-dimensional array is actually an array in which each element is a one- dimensional array
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  6 Obtaining the Lengthsof Two- Dimensional Arrays (Contd…)  The length of an array x is the number of elements in the array, which can be obtained using x.length  x[0], x[1], . . . , and x[x.length-1]  x[0].length, x[1].length, . . . , and x[x.length-1].length
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  7 Ragged Arrays  Eachrow in a two-dimensional array is itself an array. Thus, the rows can have different lengths. An array of this kind is known as a ragged array
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  8 create a raggedarray  int[][] triangleArray = new int[5][]; triangleArray[0] = new int[5]; triangleArray[1] = new int[4]; triangleArray[2] = new int[3]; triangleArray[3] = new int[2]; triangleArray[4] = new int[1];
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  9 Processing Two-Dimensional Arrays Nested for loops are used to process a two-dimensional array  Initializing arrays with input values  java.util.Scanner input = new Scanner(System.in); System.out.println("Enter " + matrix.length + " rows and " + matrix[0].length + " columns: "); for (int row = 0; row < matrix.length; row++) { for (int column = 0; column < matrix[row].length; column++) { matrix[row][column] = input.nextInt(); } }
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  10 Processing Two-Dimensional Arrays (Contd…) Other Processes  Initializing arrays with random values  Printing arrays  Summing all elements  Summing elements by column  Which row has the largest sum?
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  11 Passing Two-Dimensional Arraysto Methods  When passing a two-dimensional array to a method, the reference of the array is passed to the method  You can pass a two-dimensional array to a method just as you pass a one- dimensional array
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  12  public classPassTwoDimensionalArray { public static void main(String[] args) { int[][] m = getArray(); // Get an array System.out.println("nSum of all elements is " + sum(m)); }  public static int[][] getArray() { Scanner input = new Scanner(System.in); int[][] m = new int[3][4]; System.out.println("Enter " + m.length + " rows and “ + m[0].length + " columns: "); for (int i = 0; i < m.length; i++) for (int j = 0; j < m[i].length; j++) m[i][j] = input.nextInt(); return m; }
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  13 Multidimensional Arrays  two-dimensionalarray consists of an array of one-dimensional arrays  Three dimensional array consists of an array of two-dimensional arrays  double[][][] scores = new double[6][5][2];  Suppose x = new int[2][2][5]  x[0] and x[1] are two-dimensional arrays  x[0][0], x[0][1], x[1][0], and x[1][1] are one-dimensional arrays and each contains five elements  x.length is 2  x[0].length and x[1].length are 2  x[0][0].length, x[0][1].length, x[1][0].length, and x[1][1].length are 5