# Limiting Ruby Numbers

**URL:** <https://www.ruby-forum.com/t/limiting-ruby-numbers/63004>\
**Category:** Ruby\
**Created:** [June 10, 2006, 11:16am UTC](https://www.ruby-forum.com/t/limiting-ruby-numbers/63004 "2006-06-10T11:16:17Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![guest](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/8dc957/32.png) [@guest](https://www.ruby-forum.com/u/guest)\
**Post date:** [June 10, 2006, 11:16am UTC](https://www.ruby-forum.com/t/limiting-ruby-numbers/63004/1 "2006-06-10T11:16:17Z")

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is there any ways to limit ruby numbers up to certain bytes? all i’ve  
read is that ruby numbers are limited to host’s free memory

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**Author:** ![guest](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/8dc957/32.png) [@guest](https://www.ruby-forum.com/u/guest)\
**Post date:** [June 10, 2006, 1:38pm UTC](https://www.ruby-forum.com/t/limiting-ruby-numbers/63004/2 "2006-06-10T13:38:58Z")

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What exactly are you trying to do? From the Fixnum documentation:

"A Fixnum holds Integer values that can be represented in a native  
machine word (minus 1 bit). If any operation on a Fixnum exceeds this  
range, the value is automatically converted to a Bignum.

Fixnum objects have immediate value. This means that when they are  
assigned or passed as parameters, the actual object is passed, rather  
than a reference to that object. Assignment does not alias Fixnum  
objects. There is effectively only one Fixnum object instance for any  
given integer value, so, for example, you cannot add a singleton  
method to a Fixnum."

Is that the answer you are looking for?

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<div class="post-metadata">

**Author:** ![guest](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/8dc957/32.png) [@guest](https://www.ruby-forum.com/u/guest)\
**Post date:** [June 10, 2006, 3:01pm UTC](https://www.ruby-forum.com/t/limiting-ruby-numbers/63004/3 "2006-06-10T15:01:49Z")

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On Jun 10, 2006, at 4:16 AM, Guest wrote:

> is there any ways to limit ruby numbers up to certain bytes? all i’ve  
> read is that ruby numbers are limited to host’s free memory

Keep watching the Ruby Q… 😉

James Edward G. II

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<div class="post-metadata">

**Author:** ![guest](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/8dc957/32.png) [@guest](https://www.ruby-forum.com/u/guest)\
**Post date:** [June 10, 2006, 10:40pm UTC](https://www.ruby-forum.com/t/limiting-ruby-numbers/63004/4 "2006-06-10T22:40:16Z")

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Guest wrote:

> is there any ways to limit ruby numbers up to certain bytes? all i’ve  
> read is that ruby numbers are limited to host’s free memory

Use a bit mask to truncate the integer:

irb(main):011:0\> ((2 \*\* 32) - 1)  
=\> 4294967295  
irb(main):012:0\> ((2 \*\* 32) - 1) & 0xFF  
=\> 255  
irb(main):013:0\> ((2 \*\* 32) - 1) & 0xFFFF  
=\> 65535  
irb(main):014:0\> ((2 \*\* 32) - 1) & 0xFFFFFF  
=\> 16777215  
irb(main):015:0\> ((2 \*\* 32) - 1) & 0xFFFFFFFF  
=\> 4294967295

For negative integers, be sure to preserve the sign by converting  
the result back into two’s complement form:

irb(main):021:0\> -1  
=\> -1  
irb(main):022:0\> -1 & 0xFF  
=\> 255  
irb(main):023:0\> ~(-1 & 0xFF) + 1  
=\> -255

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