import strings
https://github.com/nature-lang/nature/blob/master/std/strings/main.n
使用示例
https://github.com/nature-lang/nature/blob/master/tests/blackbox/cases/20230901_00_strings.n
fn from(cptr p):string
基于 c 字符串创建一个 nature 字符串
fn find_char(string s, u8 char, int after):int
fn find(string s, string sub, int after):int
fn reverse(string s):string
fn rfind(string s, string sub, int before):int
从右侧开始查找,且 index < before 的 sub str
fn ends_with(string s, string ends):bool
fn starts_with(string s, string starts):bool
fn contains(string s, string sub):bool
fn finish(string s, string cap):string
fn find(string s, string sub):int
fn slice(string s, int start, int end):string
fn split(string s, string separator):[string]
fn join([string] list, string separator):string
fn ascii(string c):u8
fn ltrim(string s, [string] list):string
fn rtrim(string s, [string] list):string
fn trim(string s, [string] list):string
fn replace(string s, string sub_old, string sub_new):string