李二狗 — @Meniny
Table of Content
字符串操作是任何一门编程语言中最常用的操作之一，Scheme 也提供了一系列 procudure 来操作字符串。
1、字符串的比较，分别有string=?、string>?、string<?、string>=?、string<=?。
这与其他语言中对 string 的比较并无不同，比较字符和长度。
例子:
(string=? "mom" "mom") <graphic> #t
(string<? "mom" "mommy") <graphic> #t
(string>? "Dad" "Dad") <graphic> #f
(string=? "Mom and Dad" "mom and dad") <graphic> #f
(string<? "a" "b" "c") <graphic> #t
注意这些比较操作是大小写敏感。相应的，大小写不敏感的版本:
procedure: (string-ci=? string1 string2 string3 ...)
procedure: (string-ci<? string1 string2 string3 ...)
procedure: (string-ci>? string1 string2 string3 ...)
procedure: (string-ci<=? string1 string2 string3 ...)
procedure: (string-ci>=? string1 string2 string3 ...)
2、从字符构造字符串，使用string过程
(string #\a) => "a"
(string #\a #\b #\c) => "abc"
注意换行字符是#\newline ,回车字符是#\return
3、重复N个字符构造字符串
(make-string) => ""
(make-string 4 #\a) =>"aaaa")
4、字符串长度 string-length
(string-length "") =>0
(string-length "dennis") => 6
5、取第N个字符，相当于java中的charAt
(string-ref "hi there" 0) <graphic> #\h
(string-ref "hi there" 5) <graphic> #\e
6、修改字符串的第N个字符
(string-Setter! "hello" 0 #\H) => "Hello"
7、拷贝字符串
(let ((str "abc"))
(eq? str (string-copy str))) => #f
(let ((str "abc"))
(equal? str (string-copy str))) => #t
8、拼接字符串，string-append
(string-append) => ""
(string-append "abc" "defg") => "abcdefg"
9、截取子串
(substring "hi there" 0 1) <graphic> "h"
(substring "hi there" 3 6) <graphic> "the"
(substring "hi there" 5 5) <graphic> ""
10、填充字符串
(let ((str (string-copy "sleepy")))
(string-fill! str #\Z)
str) <graphic> "ZZZZZZ"
11、与list的相互转换
(string->list "") <graphic> ()
(string->list "abc") <graphic> (#\a #\b #\c)
(list->string '()) <graphic> ""
(list->string '(#\a #\b #\c)) <graphic> "abc"
(list->string
(map char-upcase
(string->list "abc"))) <graphic> "ABC"
