bro学习笔记之字符串函数

sub_bytes (s: string, start: count, n: count): string   从s中取位置为start开始的n个子串51Testing软件测试网9}G2_O]aj
 例：sub_bytes("abcdefg",3,2) ==》cd 51Testing软件测试网^
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match_pattern(s: string, p:pattern): pattern_match_result  ==> matched = T or F, str = 匹配串, ōff = 匹配串在原字符串中的起始位置51Testing软件测试网2?qmP ['D!Q
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xt@y4b7} neJ1KM0subst(s: string, from: pattern, to: string): string  用to 替代 from51Testing软件测试网3Y&}5M&F,L*q
 例：subst("abcd", /a/, to: *) ==> *bcd

x3N{m-A&A~6n/F0subst_string%(s: string, from: string, to: string%): string51Testing软件测试网"e9v v;G%H6yW
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 例：subst("abcd", "a", to: *) ==> *bcd51Testing软件测试网Ls{T:@&J
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cut_tail(s: string, tail_len: count): string  去掉后面tail_len个字符51Testing软件测试网}'Ri"u.O vb9~K
 例：cut_tail("abcd",1) ==>abc  51Testing软件测试网'{YZ?_-R}C
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byte_len("abcd") 求字符串长度51Testing软件测试网#Z]6J%\2Ea