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# Strings \(Unicode\)
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A _string_ is a fixed-length array of characters. It prints using
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doublequotes, where doublequote and backslash characters within the
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string are escaped with backslashes. Other common string escapes are
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supported, including `\n` for a linefeed, `\r` for a carriage return,
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octal escapes using `\` followed by up to three octal digits, and
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hexadecimal escapes with `\u` \(up to four digits\). Unprintable
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characters in a string are normally shown with `\u` when the string is
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printed.
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> +\[missing\] in \[missing\] documents the fine points of the syntax of
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> strings.
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The `display` procedure directly writes the characters of a string to
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the current output port \(see \[missing\]\), in contrast to the
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string-constant syntax used to print a string result.
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Examples:
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```racket
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> "Apple"
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"Apple"
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> "\u03BB"
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"λ"
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> (display "Apple")
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Apple
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> (display "a \"quoted\" thing")
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a "quoted" thing
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> (display "two\nlines")
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two
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lines
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> (display "\u03BB")
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λ
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```
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A string can be mutable or immutable; strings written directly as
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expressions are immutable, but most other strings are mutable. The
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`make-string` procedure creates a mutable string given a length and
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optional fill character. The `string-ref` procedure accesses a character
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from a string \(with 0-based indexing\); the `string-set!` procedure
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changes a character in a mutable string.
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Examples:
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```racket
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> (string-ref "Apple" 0)
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#\A
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> (define s (make-string 5 #\.))
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> s
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"....."
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> (string-set! s 2 #\λ)
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> s
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"..λ.."
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```
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String ordering and case operations are generally _locale-independent_;
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that is, they work the same for all users. A few _locale-dependent_
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operations are provided that allow the way that strings are case-folded
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and sorted to depend on the end-user’s locale. If you’re sorting
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strings, for example, use `string<?` or `string-ci<?` if the sort result
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should be consistent across machines and users, but use
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`string-locale<?` or `string-locale-ci<?` if the sort is purely to order
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strings for an end user.
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Examples:
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```racket
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> (string<? "apple" "Banana")
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#f
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> (string-ci<? "apple" "Banana")
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#t
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> (string-upcase "Straße")
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"STRASSE"
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> (parameterize ([current-locale "C"])
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(string-locale-upcase "Straße"))
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"STRAßE"
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```
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For working with plain ASCII, working with raw bytes, or
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encoding/decoding Unicode strings as bytes, use byte strings.
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> +\[missing\] in \[missing\] provides more on strings and string
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> procedures.
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