string.upper(s)

字符串全部转为大写字母

local name = "admin"
local upper = string.upper(name)
print("upper="..upper)

string.lower(s)

字符串全部转为小写字母

local lower = string.lower("ADMIN")
print("ADMIN lower="..lower)

string.len(s)

获取字符串长度

-- len=0
local len1 = string.len("")
-- len=5
local len2 = string.len("admin")
print("len1="..len1.." len2="..len2)

string.reverse(s)

字符串反转

-- 字符串反转
local reverse = string.reverse("123456789")
-- 123456789 reverse=987654321
print("123456789 reverse="..reverse)

string.rep(s, n, sep)

s: 原始字符串
n: 重复次数
sep: 分隔符

-- 重复次数
local rep = string.rep("abc",2)
-- abcabc
print("rep="..rep)

-- 重复次数 使用分隔符
local rep = string.rep("abc",2,"-")
-- abc-abc
print("rep="..rep)

string.gsub(s, pattern, repl, n)

功能：替换字符串
s: 原始字符串
pattern: 替换表达式
repl: 替换的值
n: 替换次数

-- home = /usr/local, user = /usr/local
local gsub = string.gsub("home = $HOME, user = $USER", "%$(%w+)", "/usr/local")
print("gsub="..gsub)

-- name=admin, name1=admin
local gsub = string.gsub("name=$name, name1=$name", "$name", "admin")
print("gsub="..gsub)

-- gsub=name=admin, name1=$name 只替换1个
local gsub = string.gsub("name=$name, name1=$name", "$name", "admin",1)
print("gsub="..gsub)

string.find(s, pattern, init, plain)

功能：查找字符串
s string 字符串
pattern string 匹配串
init number 从哪个位置开始
plain boolean 是否使用文本匹配 true:只匹配文本 false:匹配正则及文本

local _start,_end = string.find("welcome to you ! glad to see you!","to")
if _start == nil then
    -- 如果不匹配 则会走这里
    print("not found !")
else
    -- find start =9 end=10
    print("find start =".._start.." end=".._end)
end

-- 只匹配文本  %u匹配大写字母
local _start,_end = string.find("Welcome to you ! Glad to see you!","%u",0,true)
if _start == nil then
    -- 如果不匹配 则会走这里
    print("not found !")
else
    -- find start =9 end=10
    print("find start =".._start.." end=".._end)
end

string.char(…)

ascii码转字符

local king = string.char(107,105,110,103);
print("king="..king)

string.byte(s, i, j)

字符转ascii码

-- k=107,i=105,n=110,g=103
print("k="..string.byte("k")..",i="..string.byte("i")..",n="..string.byte("n")..",g="..string.byte("g"))

string.match(s, pattern, init)

如果匹配返回第1个匹配字符串
不匹配返回nil

-- %a+ 匹配任何字母配对 只匹配字母  数字也不包括
local first_match_str = string.match("Welcome to you ! Glad to see you!", "%a+")
-- first_match_str=Welcome
print("first_match_str="..first_match_str)

string.sub(s, i, j)

字符串截取

local twothree = string.sub("123456",2,3)
-- twothree=23
print("twothree="..twothree)

string.format(formatstring, …)

local format = string.format("name=%s , age=%d , address=%s","admin",22,"zj")
print("format="..format)