What are the size limits of variables in Ruby?

Question

I would like to know the size limit of variables of the following types:

• String - How many characters can I have in a single string?
• Integer and Float - What is the largest and smallest number that can be represented?
• Array - What is the highest number of indexes I can have in a single array?
• Hash - What the largest number of pairs (key:value) I can have in one hash?

Answer 1

Since it sometimes depends on its architecture (32 or 64 bits), I set the limits as defined in the language code (when existing):

String:

• 32 bits: 2**31 - 1
• 64 bits: 2**63 - 1
• Source: https://stackoverflow.com/questions/3638622/do-ruby-objects-have-a-size-limit

Integer:

• Maximum: (2**(0.size * 8 -2) -1)
• Minimum: -(2**(0.size * 8 -2))
• Source: https://stackoverflow.com/questions/535721/ruby-max-integer

Float:

• Maximum: usually is 1.7976931348623157e+308
• Minimum: usually is 2.2250738585072014e-308
• Source: http://www.ruby-doc.org/core-2.1.1/Float.html

Array/Hash:

• There is no limit set. The limit is the amount of memory available for the process.
• Source: https://stackoverflow.com/questions/3687517/array-size-too-big-ruby

Answer 2

String => theoretical limit of 2³¹ - 1 (32 bits) or 2⁶³ - 1 (64 bits). I want to see someone manage to allocate a string this size

Integer => In thesis Ruby can change the representation and have infinite values

Float => Usually limited by architecture. Generally between 1.7976931348623158e+308 and 2.2250738585072014e-308

Array => There is no theoretical limit. In practice you can’t even use near the limit. In 32 bits there is a total limit of 4GB virtual memory. You won’t be able to create one array with 2³¹ - 1 even if each element contains only 1 byte and in Ruby as everything is reference, this is far from possible. In 64 bits if you have 2⁶³ - 1 elements, will need a lot underneath (certainly this volume is much bigger) 250EB (Exabytes). Forget it

Hash => essentially the same Although you need even more memory. But again, don’t worry so much about this limit, the practical limit comes first