Here is a PHP program to display the boundary elements of a given matrix. Boundary elements are the outsider elements of a matrix. Here the elements are of minimum and maximum rows with minimum columns and maximum columns.

### The below is an example for boundary elements of a matrix given below:

1 2 3 4 1 2 3 42 3 4 5 To 2 53 4 5 6 3 64 5 6 7 4 5 6 7

Here there are 4 rows and 4 columns. So boundary elements will be of the first row and last row (here 4th row) with the first column and last column (here 4th column).

## PHP Program to Display The Boundary Elements of a Given Matrix

<html> <body> <?php echo "<b>The matrix is given below:-</b>"."<br>"; $a=array(array()); $rows=4; $cols=4; for($i=0;$i<$rows;$i=$i+1) { for($j=0;$j<$cols;$j=$j+1) { $a[$i][$j]=$i+$j+1; echo $a[$i][$j]." "; } echo "<br>"; } echo "<b>The matrix with boundary elements is given below:-</b>"."<br>";//here <b></b>is using to define a text in bold style for($i=0;$i<$rows;$i=$i+1) { for($j=0;$j<$cols;$j=$j+1) { if($i==0||$i==$rows-1||$j==0||$j==$cols-1) { echo $a[$i][$j]." "; } else { echo "   "; } } echo "<br>"; //here this is creating a new line } ?> </body> </html>

### Output:

The matrix is given below:-1 2 3 4 2 3 4 5 3 4 5 6 4 5 6 7The matrix with boundary elements is given below:-1 2 3 4 2 5 3 6 4 5 6 7

Here we have created a 4*4 matrix with a statement ($a[$i][$j]=$i+$j+1) and then displayed that matrix. After displaying the matrix, we have displayed the boundary elements with spaces of the original matrix based on a condition (here either $i==0(row index number=0) or $i==$rows-1 or $j==0 (column index number=0),$j==$cols-1). Here $nbsp is creating a space.