ruby 是否有www.example.com的反义词String.next?[重复]

46qrfjad 于 2023-05-22 发布在 Ruby

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What is the opposite of string.next?（1个答案）
9年前关闭。
Ruby中next的反义词是什么？我试图找到一个类似prev的函数，它不存在。
"b".prev == "a"，就像"a".next == "b"

# A grad student at a local university thinks he has discovered a formula to
# predict what kind of grades a person will get. He says if you own less than 
# 10 books, you will get a "D". If you own 10 to 20 books, you will get a "C", 
# and if you own more than 20 books, you will get a "B".
# He further hypothesizes that if you actually read your books, then you will
# get a full letter grade higher in every case.
#
# grade(4,  false)  # => "D"
# grade(4,  true)   # => "C"
# grade(15, true)   # => "B"

ruby

来源：https://stackoverflow.com/questions/16801240/is-there-an-opposite-of-string-next

1条答案

按热度按时间

r1zk6ea11#

如果您的案例仅限于唯一字符，则以下内容将允许您获取上一个或下一个字符：

def next_char(c)
  (c.chr.ord + 1).chr
end

def prev_char(c)
  (c.chr.ord - 1). chr
end

puts next_char('A')
puts prev_char('B')

然而，当你处理等级时，我会选择一种等级枚举。例如，看一下blog post可能实现。
参考：

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ruby 是否有www.example.com的反义词String.next?[重复]

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