C++: string_view: Deep dive Jasmine Lopez Prithvi Okade 1Topics • Motivation • Performance benefits & basics • string_view: Constructors, useful functions • string vs. string_view and their interoperability interoperability • When to use string_view • Using string_view safely • Intro to span • span vs. string_view • Case study of an optimization using string_view. 2Motivation • Consider a function foo immutable string. • In C++ we generally will create it with following signature. 3 void foo(const std::string& str); string existing_str; foo(existing_str); foo("hello this is a long string"); This

学习目标 1. 掌握 Java 数组的概念 2. 学会一维数组和二维数组的使用；认识 Arrays 类，掌握操 作数组相关方法 3. 掌握 Java 字符串的概念，字符串与数组的关系；学会 String 类常用字符串操作方法 大纲 数组的概念 一维数组 二维数组 字符串 大纲 数组的概念 一维数组 二维数组 字符串 大纲 数组的概念 一维数组 二维数组 字符串 接下来… 数组的概念 ▶ 字符串是用一对双引号括起来的字符序列。Java 语言中， 字符串常量或变量均用类实现。 ▶ String 对象是不可变的。String 类每一个看起来会修改 String 值的方法，实际上都创建了一个新的对象，以包含修 改后的字符串内容。 1 String s = new String("hello java"); 2 s.toUpperCase(); 3 System.out.println(s); println(s); 大纲 数组的概念 一维数组 二维数组 字符串 理解 Java 字符串 CODE ± String.java Part 1 1 public final class String 2 implements java.io.Serializable, Comparable<String>, CharSequence { //1 3 /** The value is used for

declaration type T struct { name string // name of the object value int // its value } gofmt will line up the columns: type T struct { name string // name of the object value int returns, if successful, a Regexp // object that can be used to match against text. func Compile(str string) (regexp *Regexp, err error) { Go's declaration syntax allows grouping of declarations. A single and it's productive to honor them and the function names they capture. Read, Write, Close, Flush, String and so on have canonical signatures and meanings. To avoid confusion, don't give your method one

48 IfThen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1310 74.3.49 in(string,):Boolean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1311 74.3.50 in(UnicodeString Operating System functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1333 75.5 String handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1333 75.6 Mathematical assign(single):variant . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1421 75.11.29 assign(UCS4String):variant . . . . . . . . . . . . . . . . . . . . . . . . . 1421 75.11.30 assign(UnicodeString):olevariant

example std::string text = "..."; text = SpellCheck(text); text = GrammarCheck(text);function composition is fundamental GrammarCheck(SpellCheck("..."))motivating example std::string SpellCheck(std::string SpellCheck(std::string text) { auto body = http::UrlEncode({"text", text}); auto response = http::Post("https://www.online-spellcheck.com", body); return response.body; }motivating example std::string SpellCheck(std::string SpellCheck(std::string text) { auto body = http::UrlEncode({"text", text}); auto response = http::Post("https://www.online-spellcheck.com", body); return response.body; }motivating example std::string SpellCheck(std::string

expect fun writeLogMessage(message: String, logLevel: LogLevel) fun logDebug(message: String) = writeLogMessage(message, LogLevel.DEBUG) fun logWarn(message: String) = writeLogMessage(message, LogLevel LogLevel.WARN) fun logError(message: String) = writeLogMessage(message, LogLevel.ERROR) ├ compiled for all platforms ├ expected platform-specific API ├ expected API can be used in the common code It expects implementation that writes the log to the standard output: internal actual fun writeLogMessage(message: String, logLevel: LogLevel) { println("[$logLevel]: $message") } In the JavaScript world, a completely

complete program. You don’t need to import a separate library for functionality like input/output or string handling. Code written at global scope is used as the entry point for the program, so you don’t need "The width is " 2 let width = 94 3 let widthLabel = label + String(width) E X P E R I M E N T Try removing the conversion to String from the last line. What error do you get? There’s an even simpler oranges) pieces of fruit." E X P E R I M E N T Use \() to include a floating-point calculation in a string and to include someone’s name in a greeting. Use three double quotation marks (""") for strings

Windows, run .\main.exe instead of ./main. Regardless of your operating system, you should see the string Hello, world! print to the terminal. If you did, then congratulations! You’ve officially written instead of a normal function. Next is “Hello, world!” which is a string. We pass this string as an argument to println!, which prints the string to the screen. Easy enough! The line ends with a semicolon (;) main() { println!("Guess the number!"); println!("Please input your guess."); let mut guess = String::new(); io::stdin().read_line(&mut guess) .expect("Failed to read line"); println!("You guessed:

vector 容器初体验 & 迭代器入门 (BV1qF411T7sd) 2. 你所不知道的 set 容器 & 迭代器分类 (BV1m34y157wb) 3. string ， string_view ， const char * 的爱恨纠葛 ( 本期 ) 4. 万能的 map 容器全家桶及其妙用举例 5. 函子 functor 与 lambda 位的，标准规定只需满足 char <= short <= int <= long <= long long 即可）。 关于 char 类型的一个冷知识 C 语言中的字符串 • 字符串 (string) 就是由字符 (character) 组成的数组。 • C 语言中，字符串用双引号 “” 包裹，字符用单引号 ‘’ 包裹 。 • char c = ‘h’; • char s[] = “hello”; std::string 应运而生 封装的 std::string 应运而生 • string 可以从 const char * 隐式构造： • string s = “hello”; • string 具有 + 、 += 、 == 等直观的运算符重载： • string(“hello”) + string(“world”) == string(“helloworld”) • string 符合 vector

 String Formatting Improvements  Standard Library Modules  std::flat_(multi)map / std::flat_(multi)set  std::mdspan  std::generator  basic_string(_view)::contains()  Construct string(_view) string(_view) From nullptr  basic_string::resize_and_overwrite()  Monadic Operations for std::optional  Stacktrace Library  Changes to Ranges Library  Changes to Views Library  std::expected  std:  String Formatting Improvements  Standard Library Modules  std::flat_(multi)map / std::flat_(multi)set  std::mdspan  std::generator  basic_string(_view)::contains()  Construct string(_view)