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02 User defined literals _f

Requirements：

1. Please don’t change main function.
2. Please implement your function/code to get Expected results.

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int main(){
    std::cout << "乐 :{} *\n"_f(5);
    std::cout << "乐 :{0} {0} *\n"_f(5);
    std::cout << "乐 :{:b} *\n"_f(0b01010101);
    std::cout << "{:*<10}"_f("卢瑟");
    std::cout << '\n';
    int n{};
    std::cin >> n;
    std::cout << "π：{:.{}f}\n"_f(std::numbers::pi_v<double>, n);
}

Expected results

乐 :5 *
乐 :5 5 *
乐 :1010101 *
卢瑟******
6
π：3.141593

Suggested environments

Compiler explorer, please add –std=c++20 to the compilation options.

My implementation

Reference code, please use browser to translate page from Chinese to English if necessary.

03 Template specification with std::formatter

Requirements：

1. Please don’t change main function.
2. Please implement your function/code to get Expected results.

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int main(){
    std::cout << "乐 :{} *\n"_f(5);
    std::cout << "乐 :{0} {0} *\n"_f(5);
    std::cout << "乐 :{:b} *\n"_f(0b01010101);
    std::cout << "{:*<10}"_f("卢瑟");
    std::cout << '\n';
    int n{};
    std::cin >> n;
    std::cout << "π：{:.{}f}\n"_f(std::numbers::pi_v<double>, n);
}

struct Frac {
   int a, b;
};

Frac f{ 1,10 };
print("{}", f);// result: 1/10

Expected results

1/10

Suggested environments

Compiler explorer, please add –std=c++20 to the compilation options.

My implementation

Reference code, please use browser to translate page from Chinese to English if necessary.

04 Class template different types of instantiation

Requirements：

1. Please don’t change main function.
2. Please implement your function/code to get Expected results.

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#include<iostream>
class ComponentBase{
protected:
    static inline std::size_t component_type_count = 0;
};
template<typename T>
class Component : public ComponentBase{
public:
    // todo...
    // Change the current template class in any way so that for any type X, if it inherits from Component

    // Then X::component type id() will get a unique id of type size t (different values should be returned for different X types)值应不同）
    // Requirements: std::type info cannot be used (the typeid keyword is disabled), and all ids are consecutive starting from 0
};
class A : public Component<A>
{};
class B : public Component<B>
{};
class C : public Component<C>
{};
int main()
{
    std::cout << A::component_type_id() << std::endl;
    std::cout << B::component_type_id() << std::endl;
    std::cout << B::component_type_id() << std::endl;
    std::cout << A::component_type_id() << std::endl;
    std::cout << A::component_type_id() << std::endl;
    std::cout << C::component_type_id() << std::endl;
}

Expected results

0
1
1
0
0
2

Suggested environments

Compiler explorer, please add –std=c++20 to the compilation options.

My implementation

Reference code, please use browser to translate page from Chinese to English if necessary.

01 Implement pipe operator

Requirements：

1. Please don’t change main function.
2. Please implement your function/code to get Expected results.

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#include <cstdio>
#include <cassert>

#include <stdexcept>
#include <iostream>
#include <functional>

struct X {
    X() { puts("X()"); }
    X(const X&) { puts("X(const X&)"); }
    X(X&&) noexcept { puts("X(X&&)"); }
    ~X() { puts("~X()"); }
};

int main() {
    {
        // scope_guard的作用之一，是让各种C风格指针接口作为局部变量时也能得到RAII支持
        // 这也是本题的基础要求
        FILE * fp = nullptr;
        try{
            fp = fopen("test.txt","a");
            auto guard = scope_guard([&] {
                fclose(fp);
                fp = nullptr;
            });

            throw std::runtime_error{"Test"};
        } catch(std::exception & e){
            puts(e.what());
        }
        assert(fp == nullptr);
    }
    puts("----------");
    {
        // 附加要求1，支持函数对象调用
        struct Test {
            void operator()(X* x) {
                delete x;
            }
        } t;
        auto x = new X{};
        auto guard = scope_guard(t, x);
    }
    puts("----------");
    {
        // 附加要求2，支持成员函数和std::ref
        auto x = new X{};
        {
            struct Test {
                void f(X*& px) {
                    delete px;
                    px = nullptr;
                }
            } t;
            auto guard = scope_guard{&Test::f, &t, std::ref(x)};
        }
        assert(x == nullptr);
    }
}

Expected results

Test
----------
X()
~X()
----------
X()
~X()

Suggested environments

Compiler explorer, please add –std=c++20 to the compilation options.

My implementation

Reference code, please use browser to translate page from Chinese to English if necessary.

01 Implement pipe operator

Requirements：

1. Please don’t change main function.
2. Please implement your function/code to get Expected results.

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int main()
{
    std::vector v{1, 2, 3};
    std::function f {[](const int& i) {std::cout << i << ' '; } };
    auto f2 = [](int& i) {i *= i; };
    v | f2 | f;
}

Expected results

1 4 9

Suggested environments

Compiler explorer, please add –std=c++20 to the compilation options.

My implementation

Reference code, please use browser to translate page from Chinese to English if necessary.

Headings

The following HTML <h1>—<h6> elements represent six levels of section headings. <h1> is the highest section level while <h6> is the lowest.

H1

H2

H3

H4

H5

H6

Paragraph

Xerum, quo qui aut unt expliquam qui dolut labo. Aque venitatiusda cum, voluptionse latur sitiae dolessi aut parist aut dollo enim qui voluptate ma dolestendit peritin re plis aut quas inctum laceat est volestemque commosa as cus endigna tectur, offic to cor sequas etum rerum idem sintibus eiur? Quianimin porecus evelectur, cum que nis nust voloribus ratem aut omnimi, sitatur? Quiatem. Nam, omnis sum am facea corem alique molestrunt et eos evelece arcillit ut aut eos eos nus, sin conecerem erum fuga. Ri oditatquam, ad quibus unda veliamenimin cusam et facea ipsamus es exerum sitate dolores editium rerore eost, temped molorro ratiae volorro te reribus dolorer sperchicium faceata tiustia prat.

Itatur? Quiatae cullecum rem ent aut odis in re eossequodi nonsequ idebis ne sapicia is sinveli squiatum, core et que aut hariosam ex eat.

Blockquotes

The blockquote element represents content that is quoted from another source, optionally with a citation which must be within a footer or cite element, and optionally with in-line changes such as annotations and abbreviations.

Blockquote without attribution

Tiam, ad mint andaepu dandae nostion secatur sequo quae. Note that you can use Markdown syntax within a blockquote.

Blockquote with attribution

Don’t communicate by sharing memory, share memory by communicating.

— Rob Pike¹

Tables

Tables aren’t part of the core Markdown spec, but Hugo supports them out-of-the-box.

Inline Markdown within tables

Code Blocks

Inline Code

This is Inline Code

Only pre

This is pre text

Code block with backticks

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8" />
        <title>Example HTML5 Document</title>
    </head>
    <body>
        <p>Test</p>
    </body>
</html>

Code block with backticks and language specified

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<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8" />
        <title>Example HTML5 Document</title>
        <meta name="description" content="Sample article showcasing basic Markdown syntax and formatting for HTML elements.">
    </head>
    <body>
        <p>Test</p>
    </body>
</html>

Code block indented with four spaces

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>Example HTML5 Document</title>
</head>
<body>
  <p>Test</p>
</body>
</html>

Code block with Hugo’s internal highlight shortcode

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>Example HTML5 Document</title>
</head>
<body>
  <p>Test</p>
</body>
</html>

Gist

List Types

Ordered List

1. First item
2. Second item
3. Third item

Unordered List

• List item
• Another item
• And another item

Nested list

• Fruit
  • Apple
  • Orange
  • Banana
• Dairy
  • Milk
  • Cheese

Other Elements — abbr, sub, sup, kbd, mark

GIF is a bitmap image format.

H₂O

Xⁿ + Yⁿ = Zⁿ

Press CTRL+ALT+Delete to end the session.

Most salamanders are nocturnal, and hunt for insects, worms, and other small creatures.