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    2d Arrays

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    amandeep651
    Two-dimensional arrays allow arrays to have more than one dimension. They consist of rows and columns, with the number of rows and columns specified as constants. A 2D array can be processed with a nested for loop, with the outer loop iterating through rows and the inner loop iterating through columns. 2D arrays can be initialized using curly braces. When passing a 2D array as a parameter, the base address and number of columns must be specified.

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    2d Arrays

    Uploaded by

    amandeep651
    116 views9 pages
    Two-dimensional arrays allow arrays to have more than one dimension. They consist of rows and columns, with the number of rows and columns specified as constants. A 2D array can be processed with a nested for loop, with the outer loop iterating through rows and the inner loop iterating through columns. 2D arrays can be initialized using curly braces. When passing a 2D array as a parameter, the base address and number of columns must be specified.

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    Two-dimensional arrays allow arrays to have more than one dimension. They consist of rows and columns, with the number of rows and columns specified as constants. A 2D array can be processed with a nested for loop, with the outer loop iterating through rows and the inner loop iterating through columns. 2D arrays can be initialized using curly braces. When passing a 2D array as a parameter, the base address and number of columns must be specified.

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    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    116 views9 pages

    2d Arrays

    Uploaded by

    amandeep651
    Two-dimensional arrays allow arrays to have more than one dimension. They consist of rows and columns, with the number of rows and columns specified as constants. A 2D array can be processed with a nested for loop, with the outer loop iterating through rows and the inner loop iterating through columns. 2D arrays can be initialized using curly braces. When passing a 2D array as a parameter, the base address and number of columns must be specified.

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    TWO-DIMENSIONAL ARRAYS

    TWO-DIMENSIONAL ARRAYS
    C++ also allows an array to have more than one dimension.

    For example, a two-dimensional array consists of a certain number of rows


    and columns:

    const int NUMROWS = 3;


    const int NUMCOLS = 7;
    int Array[NUMROWS][NUMCOLS]; 0 1 2 3 4 5 6
    0 4 18 9 3 -4 6 0
    1 12 45 74 15 0 98 0
    2 84 87 75 67 81 85 79

    Array[2][5] 3rd value in 6th column


    Array[0][4] 1st value in 5th column

    The declaration must specify the number of rows and the number of columns,
    and both must be constants.
    PROCESSING A 2-D ARRAY
    A one-dimensional array is usually processed via a for loop. Similarly, a two-
    dimensional array may be processed with a nested for loop:

    for (int Row = 0; Row < NUMROWS; Row++) {


    for (int Col = 0; Col < NUMCOLS; Col++) {
    Array[Row][Col] = 0;
    }
    }

    Each pass through the inner for loop will initialize all the elements of the current
    row to 0.

    The outer for loop drives the inner loop to process each of the array's rows.
    INITIALIZING IN DECLARATIONS
    int Array1[2][3] = { {1, 2, 3} , {4, 5, 6} };
    int Array2[2][3] = { 1, 2, 3, 4, 5 };
    int Array3[2][3] = { {1, 2} , {4 } };

    If we printed these arrays by rows, we would find the following initializations


    had taken place:

    Rows of Array1:
    1 2 3 for (int row = 0; row < 2; row++) {
    4 5 6 for (int col = 0; col < 3; col++) {
    cout << setw(3)
    Rows of Array2:
    1 2 3 << Array1[row][col];
    4 5 0
    }

    Rows of Array3: cout << endl;


    1 2 0 }
    4 0 0
    EXAMPLE: INPUT USING CIN
     Nested for loops are often used when
    inputting and assigning values to a two-dimensional array.
     Nested loops are generally useful for getting around the 2D
    arrays…

    for (int i=0; i<RSIZE; ++i) //every row


    for (int j=0; j<CSIZE; ++j )//every col
    cin >> table[i][j];
    2-D ARRAYS AS PARAMETERS
    When passing a two-dimensional array as a parameter, the base address is
    passed, as is the case with one-dimensional arrays.

    But now the number of columns in the array parameter must be specified.
    This is because arrays are stored in row-major order, and the number of
    columns must be known in order to calculate the location at which each row
    begins in memory:

    address of element (r, c) = base address of array


    + r*(number of elements in a row)*(size of an
    element)
    + c*(size of an element)

    void Initialize(int TwoD[][NUMCOLS], const int NUMROWS) {


    for (int i = 0; i < NUMROWS; i++) {
    for (int j = 0; j < NUMCOLS; j++)
    TwoD[i][j] = -1;
    }
    }
    FUNCTION TO DISPLAY CONTENT OF A TWO
    DIMENSIONAL ARRAY A

    #include <iostream>
    #include <iomanip>
    using namespace std;

    void print(int A[][3],int N, int M)


    {
    for (int R = 0; R < N; R++){
    cout <<endl;
    for (int C = 0; C < M; C++)
    cout << setw(10) <<A[R][C];
    }
    }
    FUNCTION TO FIND THE SUM OF TWO DIMENSIONAL
    ARRAYS A AND B

    void addition(int A[][3], int B[][3],int N, int M)


    {
    for(int R=0;R<N;R++){

    cout<<endl;
    for(int C=0;C<M;C++)
    cout<<setw(10) <<A[R][C]+B[R][C];
    }
    }
    FUNCTION TO FIND & DISPLAY SUM OF ROWS & SUM
    OF COLS. OF A 2D ARRAY A

    void SumRowCol(int A[][20], int N, int M)


    {
    for(int R=0;R<N;R++)
    {
    int SumR=0;
    for(int C=0;C<M;C++)
    SumR+=A[R][C];
    cout<<"Row("<<R<<")="<<SumR<<endl;
    }
    }

    for(int R=0;R<M;R++)
    {
    int SumC=0;
    for(int C=0;C<N;C++)
    SumC+=A[C][R];
    cout<<"Column("<<R<<")="<<SumC<<endl;
    }
    }

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