Thread: Chapter 4 Exercise 1 View Single Post
July 5th, 2016, 11:40 AM
ajjp5o7
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Chapter 4 Exercise 1

The solution in the book to exercise 4.1 is a hard coded listing of prime numbers.
I'm trying to put together a function that determines if the number is prime and then echos "Yes" or "No".
Here is where I'm hosting the exercise:

http://ajjpreble.com/learning-php/exercise4-1.php

And Here is the code I've used:

PHP Code:
``` <!doctype html> <html> <head> <meta charset="utf-8"> <link rel="stylesheet" type="text/css" href="common.css" /> <title>Exercise 4.1</title> <style type="text/css"> th { text-align: left; background-color: #999; } th, td { padding:0.4em;} tr.alt td { background: #ddd; } </style> </head> <table> <tr> <th>Number</th> <th>Parity</th> <th>Prime</th> </tr> <?php \$iterations = 10; for (\$num = 1; \$num <= \$iterations; \$num++ )  { ?> <tr<?php if ( \$num % 2 != 0 ) echo ' class="alt" ' ?>> <td><?php echo \$num ?></td> <td> <?php      if (\$num%2 == 0 ) {         echo "Even";         }     else {         echo "Odd";         }      ?> </td> <td>  <?php  //1 is not prime. See: [url]http://en.wikipedia.org/wiki/Prime_number#Primality_of_one[/url]    if(\$num == 1)         echo "No";          //2 is prime (the only even number that is prime)     if(\$num == 2)         echo "Yes";           /**      * if the number is divisible by two, then it's not prime and it's no longer      * needed to check other even numbers      */     if(\$num !=2 && \$num % 2 == 0) {         echo "No";     }         \$primeIterations = ceil(sqrt(\$num)); for (\$divisor = 3 ; \$divisor <= \$primeIterations; \$divisor = \$divisor+2 ) {     if  ( \$num%\$divisor == 0) echo "Yes";     else echo "No"; } ?> </td> </tr> <?php } ?> </table> <body> </body> </html> ```
Could anyone give me some input?
Thank you