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

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

 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)

2、ini 配置文件指定自定义 Realm 实现(shiro-realm.ini) String getName(); //返回一个唯一的 Realm 名字 boolean supports(AuthenticationToken token); //判断此 Realm 是否支持此 Token AuthenticationException; //根据 Token 获取认证信息 public class MyRealm1 implements Realm { @Override public String getName() { return "myrealm1"; } @Override public boolean supports(AuthenticationToken en token) throws AuthenticationException { String username = (String)token.getPrincipal(); //得到用户名 String password = new String((char[])token.getCredentials()); //得到密码 if(

16.4 Result . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 16.5 String . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 16.6 Vec . . . bytes, similar to &[u8]. • String is an owned buffer of UTF-8 encoded bytes, similar to Vec. fn main() { let s1: &str = "Світ"; println!("s1: {s1}"); let mut s2: String = String::from("Привіт "); println бінарному файлі програми. • Тип String в Rust — це оболонка навколо вектора байтів. Як і у випадку з Vec, він знаходиться у володінні. • Як і у багатьох інших типів, String::from() створює рядок із рядкового

16.4 Result . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 16.5 String . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 16.6 Vec . . . [ & � � � . • String is an owned buffer of UTF-8 encoded bytes, similar to VecString = String::from ) " � � � � � � � � � � � . � � � � � � � � � � � � � � � String ) ” Hello ” ( � � � � � � � � � � � � � � � � � � � � � � � � � . • � � � � � � � � � String � � wrapper � � � � � � � � � � � � � � � � � �

Handling Phil Nash Error2018 2019series disappointments of a (total) Part 1int parse_int(std::string_view number)// TODO: +, -, digit separators? int acc = 0; for(char c : number) { *= 10; acc += c-'0'; } return acc; } int parse_int(std::string_view number) {int parse_int(std::string_view number) { int acc = 0; for(char c : number) { if(c < 42 0bool is_int(std::string_view number) { for(char c : number) { if(c < '0' || c > '9') return false; } return true; }bool is_int(std::string_view number) { for(char

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 7 String Services 71 7.1 string —常见的字符串操作 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 8.14 UserString —Class wrapper for string objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 8.15 types —Names for built-in equivalent to isinstance(obj, (str, unicode)). 2.3 新版功能. bin(x) Convert an integer number to a binary string. The result is a valid Python expression. If x is not a Python int object, it has to define an __index__()

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 7 String Services 71 7.1 string —常见的字符串操作 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 8.14 UserString —Class wrapper for string objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 8.15 types —Names for built-in equivalent to isinstance(obj, (str, unicode)). 2.3 新版功能. bin(x) Convert an integer number to a binary string. The result is a valid Python expression. If x is not a Python int object, it has to define an __index__()

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 7 String Services 71 7.1 string —常见的字符串操作 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 8.14 UserString —Class wrapper for string objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 8.15 types —Names for built-in equivalent to isinstance(obj, (str, unicode)). 2.3 新版功能. bin(x) Convert an integer number to a binary string. The result is a valid Python expression. If x is not a Python int object, it has to define an __index__()