Before I set about to writing this myself, has anyone seen a ruby implementation of the following behavior?
在我开始自己编写之前，有没有人看过以下行为的ruby实现？
puts 7.nextprime(); #=> 11
puts 7.previousprime(); #=> 5
puts 7.isprime(); #=> true
Obviously this kind of thing would be ugly for large numbers but for integers never exceeding a few thousand (the common instance for me) a sensible implementation is doable, hence the question.
显然，对于大数字来说，这种事情会很难看，但对于从不超过几千的整数（对我来说是常见的例子）来说，合理的实现是可行的，因此这个问题。
2 个解决方案
#1
10
Ruby comes with a built-in Prime class that allows you to iterate through primes starting at 1, but I see no way to initialize it with a starting value other than 1, nor a predicate check to determine whether or not a number is prime. I'd say go for it, though you should keep in mind that math in Ruby can be slow and if performance is a factor you may be better off considering writing it as a C or Java extension. Here's an example of how to use RubyInline to generate primes in C.
Ruby附带了一个内置的Prime类，它允许你从1开始迭代素数，但我看不到用1以外的起始值初始化它，也没有用谓词检查确定数字是否为素数。我要说的是，尽管你应该记住，Ruby中的数学运算速度很慢，如果性能是一个因素，那么考虑将其编写为C或Java扩展可能会更好。这是一个如何使用RubyInline在C中生成素数的示例。
Also, I suggest you avoid using the method name 7.isprime - the convention in Ruby is 7.prime?.
另外，我建议你避免使用方法名称7.isprime - Ruby中的约定是7.prime？。
#1
10
Ruby comes with a built-in Prime class that allows you to iterate through primes starting at 1, but I see no way to initialize it with a starting value other than 1, nor a predicate check to determine whether or not a number is prime. I'd say go for it, though you should keep in mind that math in Ruby can be slow and if performance is a factor you may be better off considering writing it as a C or Java extension. Here's an example of how to use RubyInline to generate primes in C.
Ruby附带了一个内置的Prime类，它允许你从1开始迭代素数，但我看不到用1以外的起始值初始化它，也没有用谓词检查确定数字是否为素数。我要说的是，尽管你应该记住，Ruby中的数学运算速度很慢，如果性能是一个因素，那么考虑将其编写为C或Java扩展可能会更好。这是一个如何使用RubyInline在C中生成素数的示例。
Also, I suggest you avoid using the method name 7.isprime - the convention in Ruby is 7.prime?.
另外，我建议你避免使用方法名称7.isprime - Ruby中的约定是7.prime？。