函式是以 fn 導入。 • 區塊會用大括號分隔，這跟在 C 和 C++ 一樣。 • main 函式是程式的進入點。 • Rust 含有衛生巨集，例如 println!。 • Rust 字串採用 UTF-8 編碼，可包含任何萬國碼字元。 我們會藉由這張投影片，試著讓學生熟悉 Rust 程式碼。在接下來的四天裡，他們會大量接觸到這些內容， 所以我們得從他們熟悉的小地方著手。 重要須知： • Rust * a)。 事實上，編譯器會偵測常數運算式的溢位，這也是本例中需要另一個函式的原因。 5.5 字串 (String) Rust 用來代表字串的型別有兩種，稍後會深入介紹。兩者「一律」都儲存 UTF-8 編碼字串。 • String - a modifiable, owned string. • &str - 這是唯讀字串。字串常量會採用此型別。 fn main() { let greeting: }", &sentence[12..13]); } 這張投影片用於介紹字串。我們稍後會深入介紹此處提及的所有內容，但目前這些就已足夠用於後續的投 影片和使用字串的練習題中。 • 字串中的無效 UTF-8 屬於 UB，而安全的 Rust 環境不允許此行為。 • String 是使用者定義的型別，具備建構函式 (::new()) 和 s.push_str(..) 等方法。 • &str 中的 &

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 8.5 UTF-8 轉換 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 完成其他的步驟。 8.5 UTF-8 轉換 如果上游文檔採用了老式編碼，那麼將其轉換爲 UTF-8 不失爲一良方。 • 用 iconv(1) 來轉換普通文本文件的編碼。 iconv -f latin1 -t utf8 foo_in.txt > foo_out.txt • 使用 w3m(1) 來把 HTML 文件轉換爲 UTF-8 普通文本文件。當你這樣做的時候，請確認在 UTF-8 locale 下執行。 下執行。 LC_ALL=en_US.UTF-8 w3m -o display_charset=UTF-8 \ -cols 70 -dump -no-graph -T text/html \ < foo_in.html > foo_out.txt 8.6 對更新套件的幾點提示 以下是對更新軟體包的幾點提示： • 保留舊的 changelog 條目 (看似顯然，但是總有可能把 dch -i 輸入爲

Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 7.3 Unicode and UTF-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 7.4 Concatenation . . . promotions for numeric and other types • Efficient support for Unicode, including but not limited to UTF-8 • Call C functions directly (no wrappers or special APIs needed) • Powerful shell-like capabilities julia> UniversalDeclarationOfHumanRightsStart = "" "" 7CHAPTER 3. VARIABLES 8 Unicode names (in UTF-8 encoding) are allowed: julia> δ = 0.00001 1.0e-5 julia> = "Hello" "Hello" In the Julia REPL and

Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 7.3 Unicode and UTF-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 7.4 Concatenation . . . promotions for numeric and other types • Efficient support for Unicode, including but not limited to UTF-8 • Call C functions directly (no wrappers or special APIs needed) • Powerful shell-like capabilities julia> UniversalDeclarationOfHumanRightsStart = "" "" 7CHAPTER 3. VARIABLES 8 Unicode names (in UTF-8 encoding) are allowed: julia> δ = 0.00001 1.0e-5 julia> = "Hello" "Hello" In the Julia REPL and

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 iCONTENTS ii 8.3 Unicode and UTF-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 8.4 Concatenation . . . promotions for numeric and other types • Efficient support for Unicode, including but not limited to UTF-8 • Call C functions directly (no wrappers or special APIs needed) • Powerful shell-like capabilities julia> UniversalDeclarationOfHumanRightsStart = "" "" 10CHAPTER 4. VARIABLES 11 Unicode names (in UTF-8 encoding) are allowed: julia> δ = 0.00001 1.0e-5 julia> = "Hello" "Hello" In the Julia REPL and

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 iCONTENTS ii 8.3 Unicode and UTF-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 8.4 Concatenation . . . promotions for numeric and other types • Efficient support for Unicode, including but not limited to UTF-8 • Call C functions directly (no wrappers or special APIs needed) • Powerful shell-like capabilities julia> UniversalDeclarationOfHumanRightsStart = "" "" 10CHAPTER 4. VARIABLES 11 Unicode names (in UTF-8 encoding) are allowed: julia> δ = 0.00001 1.0e-5 julia> = "Hello" "Hello" In the Julia REPL and

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 iCONTENTS ii 8.3 Unicode and UTF-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 8.4 Concatenation . . . promotions for numeric and other types • Efficient support for Unicode, including but not limited to UTF-8 • Call C functions directly (no wrappers or special APIs needed) • Powerful shell-like capabilities julia> UniversalDeclarationOfHumanRightsStart = "" "" 10CHAPTER 4. VARIABLES 11 Unicode names (in UTF-8 encoding) are allowed: julia> δ = 0.00001 1.0e-5 julia> = "Hello" "Hello" In the Julia REPL and

Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 8.3 Unicode and UTF-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 8.4 Concatenation . . . promotions for numeric and other types • Efficient support for Unicode, including but not limited to UTF-8 • Call C functions directly (no wrappers or special APIs needed) • Powerful shell-like capabilities julia> UniversalDeclarationOfHumanRightsStart = "" "" 10CHAPTER 4. VARIABLES 11 Unicode names (in UTF-8 encoding) are allowed: julia> δ = 0.00001 1.0e-5 julia> = "Hello" "Hello" In the Julia REPL and

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 iCONTENTS ii 8.3 Unicode and UTF-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 8.4 Concatenation . . . promotions for numeric and other types • Efficient support for Unicode, including but not limited to UTF-8 • Call C functions directly (no wrappers or special APIs needed) • Powerful shell-like capabilities julia> UniversalDeclarationOfHumanRightsStart = "" "" 10CHAPTER 4. VARIABLES 11 Unicode names (in UTF-8 encoding) are allowed: julia> δ = 0.00001 1.0e-5 julia> = "Hello" "Hello" In the Julia REPL and

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 iCONTENTS ii 8.3 Unicode and UTF-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 8.4 Concatenation . . . promotions for numeric and other types • Efficient support for Unicode, including but not limited to UTF-8 • Call C functions directly (no wrappers or special APIs needed) • Powerful shell-like capabilities julia> UniversalDeclarationOfHumanRightsStart = "" "" 10CHAPTER 4. VARIABLES 11 Unicode names (in UTF-8 encoding) are allowed: julia> δ = 0.00001 1.0e-5 julia> = "Hello" "Hello" In the Julia REPL and