Library

Collaboration diagram for Library:

Functions
void	map_demo ()
void	variant_demo ()
void	clamp_demo ()
void	dynamic_memory_17 ()
void	string_view_demo ()

Detailed Description

lang17

Function Documentation

clamp_demo()

void clamp_demo

(

)

clamp(x, low, high) == x < low ? low : x > high ? high : x;

Definition at line 510 of file 17.cpp.

{
    static_assert(__cpp_lib_clamp);
    assert(clamp(0, 1, 3) == 1);
    assert(clamp(2, 1, 3) == 2);
    assert(clamp(4, 1, 3) == 3);
}

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dynamic_memory_17()

void dynamic_memory_17

(

)

Definition at line 519 of file 17.cpp.

{
    int d[2] = {10, 11};
    unique_ptr<int[]> u1(d);
    assert(u1.get()[0] == 10); // C++11
    assert(u1[1] == 11);
    assert((bool)u1);
    u1.release();
    const shared_ptr<int> s1{0};
    //cout << s1.element_type.name() << endl;
    //cout << typeid(s1.weak_type).name() << endl;
    assert(typeid(reinterpret_pointer_cast<shared_ptr<int>>(s1)).name()
           == string("St10shared_ptrIS_IiEE"));
    vector<int> s = {5, 7, 4, 2, 8, 6, 1, 9, 0, 3};
 
    // https://en.cppreference.com/w/cpp/numeric/valarray/deduction_guides
    int a[] = {1, 2, 3};
    valarray va(a, 3); // uses explicit deduction guide
    static_assert(is_integral_v<remove_reference<decltype(va[0])>::type>);
}

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map_demo()

void map_demo

(

)

https://en.cppreference.com/w/cpp/container/map/extract

https://en.cppreference.com/w/cpp/container/map/insert

https://en.cppreference.com/w/cpp/container/map/merge

Definition at line 452 of file 17.cpp.

{
    map<int, string> m{{1, "mango"}, {2, "papaya"}, {3, "guava"}};
    auto nh = m.extract(2);
    nh.key() = 4;
    m.insert(move(nh));
    // m == {{1, "mango"}, {3, "guava"}, {4, "papaya"}}
 
    set<int> src {1, 3, 5};
    set<int> dst {2, 4, 5};
    dst.merge(src);
    // src == { 5 }
    // dst == { 1, 2, 3, 4, 5 }
}

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string_view_demo()

void string_view_demo

(

)

Definition at line 541 of file 17.cpp.

{
    static_assert(__cpp_lib_string_view);
    string s = "abcd";
    string_view v = s;
    assert(v.data()  == s.c_str());
    assert(v.substr(1, 2).data() >= s.c_str());
    assert(v.substr(1, 2).data() <= s.c_str() + s.length());
}

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variant_demo()

void variant_demo

(

)

variant

visit

Definition at line 476 of file 17.cpp.

{
    variant<int, float> v, w;
    v = 12; // v contains int
    int i = get<int>(v);
    w = get<int>(v);
    w = get<0>(v); // same effect as the previous line
    w = v; // same effect as the previous line
 
    // get<double>(v); // error: no double in [int, float]
    // get<3>(v); // error: valid index values are 0 and 1
 
    try {
        get<float>(w); // w contains int, not float: will throw
    } catch (const bad_variant_access&) {}
 
    using namespace literals;
 
    variant<string> x("abc");
 
    // converting constructors work when unambiguous
    x = "def"; // converting assignment also works when unambiguous
 
    variant<string, void const*> y("abc");
 
    // casts to void const * when passed a char const *
    assert(holds_alternative<void const*>(y));
    y = "xyz"s;
    assert(holds_alternative<string>(y));
 
    auto inc = [](int a) -> int { return a + 1; };
    assert(visit(inc, (variant<int>)1) == 2);
}

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