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
很多答案只接受单字符分隔符,或者不能很好地处理边缘情况(例如空分隔符),所以我认为我将提供一个更明确的解决方案。
这里有两个函数,gsplit和split,改编自Scribunto MediaWiki扩展中的代码,用于维基百科等维基。该代码在GPL v2下获得许可。我已经更改了变量名,并添加了注释,使代码更容易理解,我还更改了代码,使用常规的Lua字符串模式,而不是Scribunto的Unicode字符串模式。原始代码在这里有测试用例。
-- gsplit: iterate over substrings in a string separated by a pattern
--
-- Parameters:
-- text (string) - the string to iterate over
-- pattern (string) - the separator pattern
-- plain (boolean) - if true (or truthy), pattern is interpreted as a plain
-- string, not a Lua pattern
--
-- Returns: iterator
--
-- Usage:
-- for substr in gsplit(text, pattern, plain) do
-- doSomething(substr)
-- end
local function gsplit(text, pattern, plain)
local splitStart, length = 1, #text
return function ()
if splitStart then
local sepStart, sepEnd = string.find(text, pattern, splitStart, plain)
local ret
if not sepStart then
ret = string.sub(text, splitStart)
splitStart = nil
elseif sepEnd < sepStart then
-- Empty separator!
ret = string.sub(text, splitStart, sepStart)
if sepStart < length then
splitStart = sepStart + 1
else
splitStart = nil
end
else
ret = sepStart > splitStart and string.sub(text, splitStart, sepStart - 1) or ''
splitStart = sepEnd + 1
end
return ret
end
end
end
-- split: split a string into substrings separated by a pattern.
--
-- Parameters:
-- text (string) - the string to iterate over
-- pattern (string) - the separator pattern
-- plain (boolean) - if true (or truthy), pattern is interpreted as a plain
-- string, not a Lua pattern
--
-- Returns: table (a sequence table containing the substrings)
local function split(text, pattern, plain)
local ret = {}
for match in gsplit(text, pattern, plain) do
table.insert(ret, match)
end
return ret
end
split函数的一些例子:
local function printSequence(t)
print(unpack(t))
end
printSequence(split('foo, bar,baz', ',%s*')) -- foo bar baz
printSequence(split('foo, bar,baz', ',%s*', true)) -- foo, bar,baz
printSequence(split('foo', '')) -- f o o
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
对于那些从“在Lua中编程”这本书的练习10.1中学习过的人来说,似乎很清楚我们不能使用后面书中解释的概念(迭代器),而且函数应该接受多个字符分隔符。
split()是一个让模式匹配不需要的内容(split)并在空字符串上返回一个空表的技巧。plainSplit()的返回更像其他语言中的split。
magic = "([%%%.%(%)%+%*%?%[%]%^%$])"
function split(str, sep, plain)
if plain then sep = string.gsub(sep, magic, "%%%1") end
local N = '\255'
str = N..str..N
str = string.gsub(str, sep, N..N)
local result = {}
for word in string.gmatch(str, N.."(.-)"..N) do
if word ~= "" then
table.insert(result, word)
end
end
return result
end
function plainSplit(str, sep)
sep = string.gsub(sep, magic, "%%%1")
local result = {}
local start = 0
repeat
start = start + 1
local from, to = string.find(str, sep, start)
from = from and from-1
local word = string.sub(str, start, from, true)
table.insert(result, word)
start = to
until start == nil
return result
end
function tableToString(t)
local ret = "{"
for _, word in ipairs(t) do
ret = ret .. '"' .. word .. '", '
end
ret = string.sub(ret, 1, -3)
ret = ret .. "}"
return #ret > 1 and ret or "{}"
end
function runSplit(func, title, str, sep, plain)
print("\n" .. title)
print("str: '"..str.."'")
print("sep: '"..sep.."'")
local t = func(str, sep, plain)
print("-- t = " .. tableToString(t))
end
print("\n\n\n=== Pattern split ===")
runSplit(split, "Exercice 10.1", "a whole new world", " ")
runSplit(split, "With trailing seperator", " a whole new world ", " ")
runSplit(split, "A word seperator", "a whole new world", " whole ")
runSplit(split, "Pattern seperator", "a1whole2new3world", "%d")
runSplit(split, "Magic characters as plain seperator", "a$.%whole$.%new$.%world", "$.%", true)
runSplit(split, "Control seperator", "a\0whole\1new\2world", "%c")
runSplit(split, "ISO Time", "2020-07-10T15:00:00.000", "[T:%-%.]")
runSplit(split, " === [Fails] with \\255 ===", "a\255whole\0new\0world", "\0", true)
runSplit(split, "How does your function handle empty string?", "", " ")
print("\n\n\n=== Plain split ===")
runSplit(plainSplit, "Exercice 10.1", "a whole new world", " ")
runSplit(plainSplit, "With trailing seperator", " a whole new world ", " ")
runSplit(plainSplit, "A word seperator", "a whole new world", " whole ")
runSplit(plainSplit, "Magic characters as plain seperator", "a$.%whole$.%new$.%world", "$.%")
runSplit(plainSplit, "How does your function handle empty string?", "", " ")
输出
=== Pattern split ===
Exercice 10.1
str: 'a whole new world'
sep: ' '
-- t = {"a", "whole", "new", "world"}
With trailing seperator
str: ' a whole new world '
sep: ' '
-- t = {"a", "whole", "new", "world"}
A word seperator
str: 'a whole new world'
sep: ' whole '
-- t = {"a", "new world"}
Pattern seperator
str: 'a1whole2new3world'
sep: '%d'
-- t = {"a", "whole", "new", "world"}
Magic characters as plain seperator
str: 'a$.%whole$.%new$.%world'
sep: '$.%'
-- t = {"a", "whole", "new", "world"}
Control seperator
str: 'awholenewworld'
sep: '%c'
-- t = {"a", "whole", "new", "world"}
ISO Time
str: '2020-07-10T15:00:00.000'
sep: '[T:%-%.]'
-- t = {"2020", "07", "10", "15", "00", "00", "000"}
=== [Fails] with \255 ===
str: 'a�wholenewworld'
sep: ''
-- t = {"a"}
How does your function handle empty string?
str: ''
sep: ' '
-- t = {}
=== Plain split ===
Exercice 10.1
str: 'a whole new world'
sep: ' '
-- t = {"a", "whole", "new", "world"}
With trailing seperator
str: ' a whole new world '
sep: ' '
-- t = {"", "", "a", "", "whole", "", "", "new", "world", "", ""}
A word seperator
str: 'a whole new world'
sep: ' whole '
-- t = {"a", "new world"}
Magic characters as plain seperator
str: 'a$.%whole$.%new$.%world'
sep: '$.%'
-- t = {"a", "whole", "new", "world"}
How does your function handle empty string?
str: ''
sep: ' '
-- t = {""}
函数如下:
function split(pString, pPattern)
local Table = {} -- NOTE: use {n = 0} in Lua-5.0
local fpat = "(.-)" .. pPattern
local last_end = 1
local s, e, cap = pString:find(fpat, 1)
while s do
if s ~= 1 or cap ~= "" then
table.insert(Table,cap)
end
last_end = e+1
s, e, cap = pString:find(fpat, last_end)
end
if last_end <= #pString then
cap = pString:sub(last_end)
table.insert(Table, cap)
end
return Table
end
这样称呼它:
list=split(string_to_split,pattern_to_match)
例如:
list=split("1:2:3:4","\:")
更多信息请点击这里: http://lua-users.org/wiki/SplitJoin
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)
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