The document discusses multidimensional arrays in C++. It provides examples of declaring and initializing 2D arrays, accessing elements, and iterating through elements using for loops. It also gives examples of user input and output of 2D arrays, including a program that takes user input to populate a 2D integer array and then displays the populated array.

1. Arrays
Multidimensional Arrays

2. Practice Problems
 Write a C++ program to find the sum and average of one
dimensional integer array.
 Write a C++ program to swap first and last element of an
integer array.
 Write a C++ program to reverse the element of an integer
array.
 Write a C++ program to find the largest and smallest element
of an array.

3. Practice Problems
 Write a C++ program to find the largest and second largest
element of an array.
 Write a C++ program to find Even and Odd elements in an
array.
 Write a C++ program to determine whether elements of an
array are prime numbers.
 Item_Code is one-dimensional array of integers. Write a C++
function to efficiently search for a data Val from Item_Code.
If Val is present in the array then the function should return
value true/1 and false/0 otherwise.

4. Multidimensional Arrays
 Arrays can be multidimensional.
 A two dimensional array consists of Rows and
Columns as we have them in a matrix.
 To declare a two-dimensional array of size x, y:
data_type arrayName [ x ] [ y ];
 Where data_type can be any valid C++ data type
and arrayName will be a valid C++ identifier.
 x represents number of Rows and y represents
number of Columns

5. Multidimensional Arrays
 A two-dimensional array can be think as a table, which
will have x number of rows and y number of columns. A
2-dimensional array a of type float, which contains
three rows and four columns can be shown as below:
float a [ 3 ] [ 4 ];

6. Multidimensional Arrays
 Every element in array a is identified by an element
name of the form a[ i ][ j ], where a is the name of the
array, and i and j are the subscripts that uniquely identify
each element in a.
 Initializing Two-Dimensional Arrays

7. Multidimensional Arrays
 Multi-dimensioned arrays may be initialized by specifying
bracketed values for each row. Following are some examples
for declaration and initialization.
int val[3][4] = {
{0, 1, 2, 3} , //initializers for row indexed by 0
{4, 5, 6, 7} , //initializers for row indexed by 1
{8, 9, 10, 11} //initializers for row indexed by 2
};
int b[4][4] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
int c[2][5] = {0}; //initialize all elements with 0

8. Example:
int main()
{
int rows=4, cols=2;
float array[rows][cols] = { {17.0, 25.5},
{23.95,41.25}, {37.25,60.5},{40.0,81.35}};
// output each array element's value
for ( int i = 0; i < rows; i++ )
for ( int j = 0; j < cols; j++ ) {
cout << "array[" << i << "][" << j << "]: ";
cout << array[i][j]<< endl;
}
}

9. Output:

10. Multidimensional Arrays
int main() {
const int ROW = 4;
const int COLUMN = 3;
int matrix[ROW][COLUMN];
for(int a = 0; a < ROW; a++)
{
for(int b = 0; b < COLUMN; b++)
{
cout << "Enter ROW " << a+1 << " COLUMN "<<b+1<<" ";
cin>>matrix[a][b];
}
}
for(int a = 0; a < ROW; a++) //display array contents
{
for(int b = 0; b < COLUMN; b++)
cout << matrix[a][b] << "t";
cout << endl;
}
}

11. Multidimensional Arrays
Output
Enter ROW 1 COLUMN 1 1
Enter ROW 1 COLUMN 2 2
Enter ROW 1 COLUMN 3 3
Enter ROW 2 COLUMN 1 4
Enter ROW 2 COLUMN 2 5
Enter ROW 2 COLUMN 3 6
Enter ROW 3 COLUMN 1 7
Enter ROW 3 COLUMN 2 8
Enter ROW 3 COLUMN 3 9
Enter ROW 4 COLUMN 1 10
Enter ROW 4 COLUMN 2 11
Enter ROW 4 COLUMN 3 12
1 2 3
4 5 6
7 8 9
10 11 12