# Duncan's blog

## September 19, 2014

### Project Euler: problem 1 (PHP) – Multiples of 3 and 5

Filed under: PHP,Project Euler — duncan @ 8:00 am

I previously blogged about this Project Euler puzzle 6 years ago, using ColdFusion.  This is my approach using PHP as a simple practical exercise for myself, and I’d appreciate any feedback on my PHP code.

Problem 1:

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.

Find the sum of all the multiples of 3 or 5 below 1000.

```<?php
\$sum = 0;

for (\$i = 1; \$i < 1000; \$i++) {
if (\$i % 3 == 0 || \$i % 5 == 0) {
\$sum += \$i;
}
}

echo \$sum;
?>
```

The only thing I really noticed was that I could have used fmod(x, y) instead of x % y == 0 to calculate the modulus values, although I didn’t see any benefit in doing so at this point, with such small integers.  However it wasn’t long before I had to do so (in the third Project Euler puzzle).

1. […] without further ado, here’s the first Project Euler puzzle, a load more will hopefully […]

Pingback by Project Euler redux | Duncan's blog — September 19, 2014 @ 8:04 am

2. Something that was pointed out to me early in the piece during my travails into PHP… as a general rule, don’t close your PHP block (“?>”) if it’s the last thing in the file: http://stackoverflow.com/questions/4410704/why-would-one-omit-the-close-tag.

Comment by dacameron — September 19, 2014 @ 10:31 am

• Cool, I’d read this in the PSR-2 coding standard, but didn’t really understand why. I’ll make sure and leave it out from now on!

Comment by duncan — September 19, 2014 @ 10:43 am

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