我需要做一个简单的字符串分割,但似乎没有一个函数,我测试的手动方式似乎不起作用。我该怎么做呢?


当前回答

下面是一个在Lua 4.0中工作的例程,返回inputstr中由sep分隔的子字符串的表t:

function string_split(inputstr, sep)
    local inputstr = inputstr .. sep
    local idx, inc, t = 0, 1, {}
    local idx_prev, substr
    repeat 
        idx_prev = idx
        inputstr = strsub(inputstr, idx + 1, -1)    -- chop off the beginning of the string containing the match last found by strfind (or initially, nothing); keep the rest (or initially, all)
        idx = strfind(inputstr, sep)                -- find the 0-based r_index of the first occurrence of separator 
        if idx == nil then break end                -- quit if nothing's found
        substr = strsub(inputstr, 0, idx)           -- extract the substring occurring before the separator (i.e., data field before the next delimiter)
        substr = gsub(substr, "[%c" .. sep .. " ]", "") -- eliminate control characters, separator and spaces
        t[inc] = substr             -- store the substring (i.e., data field)
        inc = inc + 1               -- iterate to next
    until idx == nil
    return t
end

这个简单的测试

inputstr = "the brown lazy fox jumped over the fat grey hen ... or something."
sep = " " 
t = {}
t = string_split(inputstr,sep)
for i=1,15 do
    print(i, t[i])
end

收益率:

--> t[1]=the
--> t[2]=brown
--> t[3]=lazy
--> t[4]=fox
--> t[5]=jumped
--> t[6]=over
--> t[7]=the
--> t[8]=fat
--> t[9]=grey
--> t[10]=hen
--> t[11]=...
--> t[12]=or
--> t[13]=something.

其他回答

就像字符串一样。Gmatch将查找字符串中的模式,这个函数将查找模式之间的内容:

function string:split(pat)
  pat = pat or '%s+'
  local st, g = 1, self:gmatch("()("..pat..")")
  local function getter(segs, seps, sep, cap1, ...)
    st = sep and seps + #sep
    return self:sub(segs, (seps or 0) - 1), cap1 or sep, ...
  end
  return function() if st then return getter(st, g()) end end
end

默认情况下,它返回由空格分隔的任何内容。

如果你在Lua中拆分字符串,你应该尝试string.gmatch()或string.sub()方法。如果知道要分割字符串的索引,则使用string.sub()方法;如果要解析字符串以找到要分割字符串的位置,则使用string.gmatch()方法。

使用Lua 5.1参考手册中的string.gmatch()示例:

 t = {}
 s = "from=world, to=Lua"
 for k, v in string.gmatch(s, "(%w+)=(%w+)") do
   t[k] = v
 end

我发现许多其他答案都有失败的边缘情况(例如。当给定的字符串包含#,{或}字符,或给定的分隔符,如%,需要转义)。下面是我使用的实现:

local function newsplit(delimiter, str)
    assert(type(delimiter) == "string")
    assert(#delimiter > 0, "Must provide non empty delimiter")

    -- Add escape characters if delimiter requires it
    delimiter = delimiter:gsub("[%(%)%.%%%+%-%*%?%[%]%^%$]", "%%%0")

    local start_index = 1
    local result = {}

    while true do
       local delimiter_index, _ = str:find(delimiter, start_index)

       if delimiter_index == nil then
          table.insert(result, str:sub(start_index))
          break
       end

       table.insert(result, str:sub(start_index, delimiter_index - 1))

       start_index = delimiter_index + 1
    end

    return result
end

你可以使用penlight图书馆。它有一个使用分隔符分割字符串的函数,输出列表。

它实现了许多我们在编程时可能需要和Lua中缺少的功能。

下面是使用它的示例。

> 
> stringx = require "pl.stringx"
> 
> str = "welcome to the world of lua"
> 
> arr = stringx.split(str, " ")
> 
> arr
{welcome,to,the,world,of,lua}
> 

你可以使用这个方法:

function string:split(delimiter)
  local result = { }
  local from  = 1
  local delim_from, delim_to = string.find( self, delimiter, from  )
  while delim_from do
    table.insert( result, string.sub( self, from , delim_from-1 ) )
    from  = delim_to + 1
    delim_from, delim_to = string.find( self, delimiter, from  )
  end
  table.insert( result, string.sub( self, from  ) )
  return result
end

delimiter = string.split(stringtodelimite,pattern)