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
我有一个非常简单的解决办法。使用gmatch()函数捕获包含除所需分隔符以外的至少一个字符的字符串。分隔符默认为任何空格(Lua中的%s):
function mysplit (inputstr, sep)
if sep == nil then
sep = "%s"
end
local t={}
for str in string.gmatch(inputstr, "([^"..sep.."]+)") do
table.insert(t, str)
end
return t
end
其他回答
这个问题已经很晚了,但如果有人想要一个处理分裂数量的版本,你想要.....
-- Split a string into a table using a delimiter and a limit
string.split = function(str, pat, limit)
local t = {}
local fpat = "(.-)" .. pat
local last_end = 1
local s, e, cap = str:find(fpat, 1)
while s do
if s ~= 1 or cap ~= "" then
table.insert(t, cap)
end
last_end = e+1
s, e, cap = str:find(fpat, last_end)
if limit ~= nil and limit <= #t then
break
end
end
if last_end <= #str then
cap = str:sub(last_end)
table.insert(t, cap)
end
return t
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: '$.%'
-- t = {"a", "whole", "new", "world"}
How does your function handle empty string?
str: ''
sep: ' '
-- t = {""}
我发现许多其他答案都有失败的边缘情况(例如。当给定的字符串包含#,{或}字符,或给定的分隔符,如%,需要转义)。下面是我使用的实现:
local function newsplit(delimiter, str)
assert(type(delimiter) == "string")
assert(#delimiter > 0, "Must provide non empty delimiter")
-- Add escape characters if delimiter requires it
delimiter = delimiter:gsub("[%(%)%.%%%+%-%*%?%[%]%^%$]", "%%%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
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.
我有一个非常简单的解决办法。使用gmatch()函数捕获包含除所需分隔符以外的至少一个字符的字符串。分隔符默认为任何空格(Lua中的%s):
function mysplit (inputstr, sep)
if sep == nil then
sep = "%s"
end
local t={}
for str in string.gmatch(inputstr, "([^"..sep.."]+)") do
table.insert(t, str)
end
return t
end
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