Zend Preparation | PHP Quiz (Learning Mode)

PHP Basics Learning Mode

Qusetions Index 105/260

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Consider the following segment of code:

<?php
    define("STOP_AT", 1024);
        $result = array();
    /* Missing code */
    {
        $result[] = $idx;
    }

    print_r($result);
?>

What should go in the marked segment to produce the following array output?

Array
{
 [0] => 1
 [1] => 2
 [2] => 4
 [3] => 8
 [4] => 16
 [5] => 32
 [6] => 64
 [7] => 128
 [8] => 256
 [9] => 512
}

foreach($result as $key => $val)

while($idx *= 2)

for($idx = 1; $idx < STOP_AT; $idx *= 2)

for($idx *= 2; STOP_AT >= $idx; $idx = 0)

while($idx < STOP_AT) do $idx *= 2

As it is only possible to add a single line of code to the segment provided, the only statement that makes sense is a for loop, making the choice either C or D. In order to select the for loop that actually produces the correct result, we must first of all revisit its structural elements. In PHP, for loops are declared as follows:

for (<init statement>; <continue until statement>; <iteration statement>)

where the is executed prior to entering the loop. The for loop then begins executing the code within its code block until the statement evaluates to False. Every time an iteration of the loop is completed, the is executed. Applying this to our code segment, the correct for statement is:

for ($idx = 1; $idx < STOP_AT; $idx *= 2)

or answer C.