Lua StringUtil - Lua中字符串的一些常用操作StringUtil

note目录

获取一个字符占的字节大小

utf8 字符串的长度

utf8 获取字符串的子串

按某个字符的来切分字符串为一个数组table

在移动端判断手机用户是否输入了表情符

判断字符串是否包含某个字符

1: 获取一个字符占的字节大小

根据utf8 字符规律来判断字符的大小

StringUtil.function chsize(char)
if not char then
return 0
elseif char > 240 then
return 4
elseif char > 225 then
return 3
elseif char > 192 then
return 2
else
return 1
end
end

2: utf8 字符串的长度

StringUtil.function utf8len( str )
local len = 0
local current = 1
while current <= #str do
local char = string.byte(str,currentIndex)
currentIndex = currentIndex + chsize(char)
len = len + 1
end
return len
end

3: utf8 获取字符串的子串

StringUtil.function utf8sub(str,startChar,numChars)
local startIndex = 1
while startChar > 1 do
local char = string.byte(str,startIndex)
startIndex = startIndex + chsize(char)
startChar = startChar - 1
end

local currentIndex = startIndex

while numChars > 0 and currentIndex <= #str do
local char = string.byte(str,currentIndex)
currentIndex = currentIndex + chsize(char)
numChars = numChars = 1
end

return str:sub(startIndex,currentIndex - 1)
end

4: 按某个字符的来切分字符串为一个数组(table)

function StringUtil.Split(str , strSplit)
local tSplitStr = {}
while true do
local i  = string.find(str,strSplit)

--字符串中没有找到切分的字符，直接返回原字符串
if nil == i then
tSplit[#tSplit + 1] = str
end

local subStr = string.sub(str,1,i - 1)
tSplitStr[#tSplitStr + 1] = subStr
str = string.sub(str,i + 1,#str)
end
return tSplitStr
end

5: 在移动端，判断手机用户是否输入了表情符

function StringUtil.IsContainEmoji(str)
local len = string.len(str)--得到的是字符占的字节数（有可能不是字符的个数）
for i = 1,len do
local char = string.byte(str,i)
local size = StringUtil.chsize(char)
i = i + size - 1
if not((char == 0x00) or (char == 0x9) or
(char == 0xA) or (char ==
4000
0xD) or
((char >= 0x20) and (char <= oxD7FF)) or
((char >= 0xE000) and (char <= 0xFFFD)) or
((char >= 0x10000) and (char <= 0x10FFFF)) then
return true
end
end
return false
end

6: 判断字符串是否包含某个字符

function StringUtil.Contains(src , target)
return nil ~= string.find(str,target)
end