Ruby Range

Ruby Range

As the range of the sequence

The first and most common use of a range is to express sequences. A sequence has a starting point, an end point, and a way to produce consecutive values in the sequence.

Ruby ''..'' ''...'' range operators. Two-point form creates a range that contains the specified highest value, and three-point form creates a range that does not contain the specified highest value.

(1..5)        #==> 1, 2, 3, 4, 5
(1...5)       #==> 1, 2, 3, 4
('a'..'d')    #==> 'a', 'b', 'c', 'd'

Sequence 1..100 is a Range object that contains references to two Fixnum objects. I f you want, you can to_a to convert the range to a list using the to_a method. Try the following example:

#!/usr/bin/ruby

$, =", "   # Array 值分隔符
range1 = (1..10).to_a
range2 = ('bar'..'bat').to_a

puts "#{range1}"
puts "#{range2}"

This results in the following:

1, 2, 3, 4, 5, 6, 7, 8, 9, 10
bar, bas, bat

Scope implements methods that allow you to traverse them, and you can examine their contents in a number of ways:

#!/usr/bin/ruby
# -*- coding: UTF-8 -*-

# 指定范围
digits = 0..9

puts digits.include?(5)
ret = digits.min
puts "最小值为 #{ret}"

ret = digits.max
puts "最大值为 #{ret}"

ret = digits.reject {|i| i < 5 }
puts "不符合条件的有 #{ret}"

digits.each do |digit|
   puts "在循环中 #{digit}"
end

Try it out . . .

This results in the following:

true
最小值为 0
最大值为 9
不符合条件的有 [5, 6, 7, 8, 9]
在循环中 0
在循环中 1
在循环中 2
在循环中 3
在循环中 4
在循环中 5
在循环中 6
在循环中 7
在循环中 8
在循环中 9

The range as a condition

The range can also be used as a conditional expression. F or example, the following snippets print lines from standard input, where the first line of each collection contains the word start and the last line contains the word end ：

while gets
   print if /start/../end/
end

Scopes can be used in case statements:

#!/usr/bin/ruby
# -*- coding: UTF-8 -*-

score = 70

result = case score
when 0..40
	"糟糕的分数"
when 41..60
	"快要及格"
when 61..70
	"及格分数"
when 71..100
   	"良好分数"
else
	"错误的分数"
end

puts result

Try it out . . .

This results in the following:

及格分数

As the range of intervals

The last use of a range is the interval test: to check that some values fall in the interval represented by the range. This is done using the equal operator

#!/usr/bin/ruby

if ((1..10) === 5)
  puts "5 lies in (1..10)"
end

if (('a'..'j') === 'c')
  puts "c lies in ('a'..'j')"
end

if (('a'..'j') === 'z')
  puts "z lies in ('a'..'j')"
end

This results in the following:

5 lies in (1..10)
c lies in ('a'..'j')