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PHP Exercises: Test whether two lines PQ and RS are parallel

PHP: Exercise-56 with Solution

Write a PHP program to test whether two lines PQ and RS are parallel.
The four points are P(x1, y1), Q(x2, y2), R(x3, y3), S(x4, y4).

Input: −100 ≤ x1, y1, x2, y2, x3, y3, x4, y4 ≤ 100
Each value is a real number with at most 5 digits after the decimal point.

Sample Solution: -

PHP Code:

<?php
 fscanf(STDIN, '%d', $n); 
for ($i = 0; $i < $n; $i++) {
    fscanf(STDIN, '%f %f %f %f %f %f %f %f', $x1, $y1, $x2, $y2, $x3, $y3, $x4, $y4);
    $pq = INF;
    if ($x2 - $x1 !== 0.0) {
        $pq = ($y2 - $y1) / ($x2 - $x1);
    }
    $rs = INF;
    if ($x4 - $x3 !== 0.0) {
        $rs = ($y4 - $y3) / ($x4 - $x3);
    } 
    echo $pq === $rs ? 'PQ and RS are parallel.' : 'PQ and RS are not parallel.';
    echo PHP_EOL;
}
?>

Sample Input:
2
1.0 0.0 3.0 2.0 2.0 2.0 0.0 0.0
4.0 3.0 10.0 7.0 14.0 5.0 8.0 10.0

Sample Output: 

PQ and RS are parallel.
PQ and RS are not parallel.

Flowchart:

Flowchart: Test whether two lines PQ and RS are parallel.

PHP Code Editor:

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Previous: Write a PHP program that accepts six numbers as input and sorts them in descending order.
Next: Write a PHP program to compute the sum of the digits of a number.

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PHP: Tips of the Day

Returns all elements in an array except for the first one

Example:

<?php
function tips_tail($items)
{
  return count($items) > 1 ? array_slice($items, 1) : $items;
}

print_r(tips_tail([1, 5, 7]));
?>

Output:

Array
(
    [0] => 5
    [1] => 7
)