[php] 列出 1~100 質數並加總

1.原理: 100 = 10*10，所以只要驗證10以內的質因數即可
2.利用常數限定數值範圍
3.計算質數總和

<?php

$number = 0;
$sum = 0;
define("MAX","100");
define("MIN", "1");

echo "This is homework for php done by Anne on April 29.<br/>";

do{
if ( $number > MIN ){
switch ($number){
case 2:
case 3:
case 5:
case 7:
echo $number." is prime <br/>";
$sum += $number;
break;
default:
if( $number % 2 !=0 ){
if ($number % 3 !=0){
if ($number % 5 !=0){
if ($number % 7 !=0){
echo $number." is prime<br/>";
$sum += $number;
}
}
}
}
break;
}
}
$number ++;
}while( $number < MAX);

echo "Sum of the primes =".$sum;
?>