Need an array-like structure in PHP with minimal memory usage

Question

In my PHP script I need to create an array of >600k integers. Unfortunately my webservers memory_limit is set to 32M so when initializing the array the script a

Answer 1

Use a string - that's what I'd do. Store it in a string on fixed offsets (16 or 20 digits should do it I guess?) and use substr to get the one needed. Blazing fast write / read, super easy, and 600.000 integers will only take ~12M to store.

base_convert() - if you need something more compact but with minimum effort, convert your integers to base-36 instead of base-10; in this case, a 14-digit number would be stored in 9 alphanumeric characters. You'll need to make 2 pieces of 64-bit ints, but I'm sure that's not a problem. (I'd split them to 9-digit chunks where conversion gives you a 6-char version.)

pack()/unpack() - binary packing is the same thing with a bit more efficiency. Use it if nothing else works; split your numbers to make them fit to two 32-bit pieces.