Question

I’m looking for the fastest way to do an integer division in php. for example, 5 / 2 should be 2 and 6 / 2 should be 3 and so on. If I simply do this, php will return 2.5 in the first case, the only solution I could find was using intval($my_number/2) – which isn’t as fast as I want it to be (but gives the expected results).

How can I do this?

EDIT:
Thanks to all of you for your ideas, I used the script posted by rubber_boots to test some of them with 10000000 iterations, here you can see the results (MAMP on a 3 or 4 year old MacBook with 2Ghz Intel core 2 duo):

start (10000000)
(int)...: 2.26 sec
floor(): 4.36 sec
int_divide(): 2.86 sec
bit-shift: 1.45 sec //note: only works for divisions through powers of 2
intval(): 4.51 sec
round() with PHP_ROUND_HALF_DOWN: 5.48 sec

until now, bit-shift is the fastest way, but I’ll leave this question open for a day to see if there are other possibilities for this…

EDIT2:
updated the results, added round() with PHP_ROUND_HALF_DOWN (thanks to Col._Shrapnel)

Answer 1

if it’s division by 2, the fastest way to do it is bit shifting.

5>>1 = 2
6>>1 = 3

and so on and so forth.
What it does is just shift the bits to the right by 1 bit, thus dividing the number by 2 and losing the rest

1110 >> 1 =  111
1011 >> 1 =  101
1011 >> 2 =   10 //division by 4
1011 << 1 =10110