string - 如何将代码点数组（Int32）转换为字符串？

Question

在 Crystal 中，可以将 String 转换为代码点的 Array(Int32)：

"abc".codepoints # [97,98,99] 

有没有办法将数组变回字符串？

Answer 1

  str     = "aа€æ∡"
  arr     = str.codepoints              # Array(Int32)
  new_str = arr.map { |x| x.chr }.join

  puts str
  puts new_str
  puts(str == new_str)

.chr 实例方法可用于获取 Int的 Unicode 代码点。然后，您.join将单个字符转换为新字符串。

Answer 2

这是一种方法：

arr   = "abc".codepoints

# The line below allocates memory and returns a "safe" pointer (ie slice) to it.
# The allocated memory is on the heap with size:
#    arr.size * sizeof(0_u8)
#    sizeof(0_u8) == 8 bits
# A slice of uint8 values (i.e. `Slice(UInt8)`) is aliased
#    in Crystal as `Bytes`.
bytes = Slice.new(arr.size, 0_u8) 
# You can also use the alias: Bytes.new(arr.size, 0_u8)

arr.each_with_index { |v, i|
  bytes[i] = v.to_u8
}
puts String.new(bytes).inspect # => "abc"

但是，以上对于多字节代码点失败：“a€æ∡”