Print boundry value

#include <iostream>

using namespace std;
const int MAX = 100;

void pritnBoundry(int arr[][MAX], int m, int n){
    for(int i = 0; i < m; i++){
        for(int j = 0; j < n; j++){
            if(i==0 || j==0 || i == n-1 || j == n-1){
                cout<<arr[i][j]<<" ";
            }
            else{
                cout<<" "<<" ";
            }
        }
        cout<<endl;
    }
}

int main(){
    int arr[4][MAX] = {{1,2,5,8},
                       {2,5,2,6},
                       {8,6,9,4},
                       {7,9,5,6}};
    pritnBoundry(arr,4,4);

    return 0;
}

Output:

1 2 5 8 
2       6 
8       4 
7 9 5 6 

Explanation:

Step 1: Include Libraries and Define Constants

#include <iostream>
using namespace std;
const int MAX = 100;

• #include <iostream>: This includes the Input/Output Stream library, which allows us to use functions like cin and cout for input and output.
• using namespace std;: This statement allows us to avoid prefixing standard C++ functions with std::. For example, we can use cout instead of std::cout.
• const int MAX = 100;: This defines a constant MAX, which is the maximum size of the 2D array’s second dimension (columns). We assume the array won’t have more than 100 columns.

Step 2: Function to Print Boundary Elements

void printBoundary(int arr[][MAX], int m, int n) {
    for(int i = 0; i < m; i++) {
        for(int j = 0; j < n; j++) {
            if(i == 0 || j == 0 || i == m-1 || j == n-1) {
                cout << arr[i][j] << " ";
            }
            else {
                cout << "  ";  // Add spaces to align output
            }
        }
        cout << endl;  // Move to the next line after printing each row
    }
}

• printBoundary Function: This function takes a 2D array arr, the number of rows m, and the number of columns n as arguments. It prints the boundary elements of the array and leaves blank spaces for non-boundary elements.
• Outer loop (for i): Iterates over the rows of the array.
• Inner loop (for j): Iterates over the columns of the array.
• Boundary Condition (if):i == 0: True for the first row.
  • j == 0: True for the first column.
  • i == m-1: True for the last row.
  • j == n-1: True for the last column.
• If any of these conditions is true, the element is part of the boundary and gets printed.
• cout << " ";: Prints two spaces to maintain alignment for non-boundary elements.
• cout << endl;: Moves to the next line after printing each row.

Step 3: Main Function

int main() {
    int arr[4][MAX] = {{1, 2, 5, 8},
                       {2, 5, 2, 6},
                       {8, 6, 9, 4},
                       {7, 9, 5, 6}};
                       
    printBoundary(arr, 4, 4);

    return 0;
}

• arr[4][MAX]: This declares a 2D array with 4 rows and a maximum of MAX columns. However, only the first 4 columns are initialized with values.
• Array Elements: The array is initialized with the following values:

{ {1, 2, 5, 8},
  {2, 5, 2, 6},
  {8, 6, 9, 4},
  {7, 9, 5, 6} }

• Calling printBoundary(arr, 4, 4): This function call passes the array, the number of rows (4), and the number of columns (4) to the printBoundary function to print the boundary elements.