update

learn_class/modern_C++_30/container1/container.cpp

@@ -0,0 +1,21 @@
+//
+// Created by light on 19-12-16.
+//
+
+#include <iostream>
+#include <map>
+#include <vector>
+#include "output_container.h"
+
+using namespace std;
+
+int main()
+{
+    map<int, int> mp{
+            {1, 1}, {2, 4}, {3, 9}};
+    cout << mp << endl;
+    vector<vector<int>> vv{
+            {1, 1}, {2, 4}, {3, 9}};
+    cout << vv << endl;
+
+}

learn_class/modern_C++_30/container1/output_container.h

@@ -0,0 +1,148 @@
+/*
+ * Written by Wu Yongwei <wuyongwei AT gmail DOT com>.
+ *
+ * Using this file requires a C++17-compliant compiler.
+ *
+ * This is free and unencumbered software released into the public domain.
+ *
+ * Anyone is free to copy, modify, publish, use, compile, sell, or
+ * distribute this software, either in source code form or as a compiled
+ * binary, for any purpose, commercial or non-commercial, and by any
+ * means.
+ *
+ * In jurisdictions that recognize copyright laws, the author or authors
+ * of this software dedicate any and all copyright interest in the
+ * software to the public domain. We make this dedication for the benefit
+ * of the public at large and to the detriment of our heirs and
+ * successors. We intend this dedication to be an overt act of
+ * relinquishment in perpetuity of all present and future rights to this
+ * software under copyright law.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * For more information, please refer to <http://unlicense.org>
+ *
+ */
+
+#ifndef OUTPUT_CONTAINER_H
+#define OUTPUT_CONTAINER_H
+
+#include <ostream>      // std::ostream
+#include <type_traits>  // std::false_type/true_type/decay_t/is_same_v
+#include <utility>      // std::declval/pair
+
+// Type trait to detect std::pair
+template <typename T>
+struct is_pair : std::false_type {};
+template <typename T, typename U>
+struct is_pair<std::pair<T, U>> : std::true_type {};
+template <typename T>
+inline constexpr bool is_pair_v = is_pair<T>::value;
+
+// Type trait to detect whether an output function already exists
+template <typename T>
+struct has_output_function {
+    template <class U>
+    static auto output(U* ptr)
+    -> decltype(std::declval<std::ostream&>() << *ptr,
+            std::true_type());
+    template <class U>
+    static std::false_type output(...);
+    static constexpr bool value =
+            decltype(output<T>(nullptr))::value;
+};
+template <typename T>
+inline constexpr bool has_output_function_v =
+        has_output_function<T>::value;
+/* NB: Visual Studio 2017 (or below) may have problems with
+ *     has_output_function_v<T>: you should then use
+ *     has_output_function<T>::value instead, or upgrade to
+ *     Visual Studio 2019. */
+
+// Output function for std::pair
+template <typename T, typename U>
+std::ostream& operator<<(std::ostream& os, const std::pair<T, U>& pr);
+
+// Element output function for containers that define a key_type and
+// have its value type as std::pair
+template <typename T, typename Cont>
+auto output_element(std::ostream& os, const T& element,
+                    const Cont&, const std::true_type)
+-> decltype(std::declval<typename Cont::key_type>(), os);
+// Element output function for other containers
+template <typename T, typename Cont>
+auto output_element(std::ostream& os, const T& element,
+                    const Cont&, ...)
+-> decltype(os);
+
+// Main output function, enabled only if no output function already exists
+template <typename T,
+        typename = std::enable_if_t<!has_output_function_v<T>>>
+auto operator<<(std::ostream& os, const T& container)
+-> decltype(container.begin(), container.end(), os)
+{
+    using std::decay_t;
+    using std::is_same_v;
+
+    using element_type = decay_t<decltype(*container.begin())>;
+    constexpr bool is_char_v = is_same_v<element_type, char>;
+    if constexpr (!is_char_v) {
+        os << "{ ";
+    }
+    if (!container.empty()) {
+        auto end = container.end();
+        bool on_first_element = true;
+        for (auto it = container.begin(); it != end; ++it) {
+            if constexpr (is_char_v) {
+                if (*it == '\0') {
+                    break;
+                }
+            }
+            if constexpr (!is_char_v) {
+                if (!on_first_element) {
+                    os << ", ";
+                } else {
+                    on_first_element = false;
+                }
+            }
+            output_element(os, *it, container, is_pair<element_type>());
+        }
+    }
+    if constexpr (!is_char_v) {
+        os << " }";
+    }
+    return os;
+}
+
+template <typename T, typename Cont>
+auto output_element(std::ostream& os, const T& element,
+                    const Cont&, const std::true_type)
+-> decltype(std::declval<typename Cont::key_type>(), os)
+{
+    os << element.first << " => " << element.second;
+    return os;
+}
+
+template <typename T, typename Cont>
+auto output_element(std::ostream& os, const T& element,
+                    const Cont&, ...)
+-> decltype(os)
+{
+    os << element;
+    return os;
+}
+
+template <typename T, typename U>
+std::ostream& operator<<(std::ostream& os, const std::pair<T, U>& pr)
+{
+    os << '(' << pr.first << ", " << pr.second << ')';
+    return os;
+}
+
+#endif // OUTPUT_CONTAINER_H

learn_class/modern_C++_30/container1/vector_l.cpp

@@ -0,0 +1,64 @@
+//
+// Created by light on 19-12-16.
+//
+#include <vector>
+#include <iostream>
+#include <queue>
+using namespace std;
+
+class Obj1 {
+public:
+    Obj1()
+    {
+        cout << "Obj1()\n";
+    }
+    Obj1(const Obj1&)
+    {
+        cout << "Obj1(const Obj1&)\n";
+    }
+    Obj1(Obj1&&)
+    {
+        cout << "Obj1(Obj1&&)\n";
+    }
+};
+
+class Obj2 {
+public:
+    Obj2()
+    {
+        cout << "Obj2()\n";
+    }
+    Obj2(const Obj2&)
+    {
+        cout << "Obj2(const Obj2&)\n";
+    }
+    Obj2(Obj2&&) noexcept
+    {
+        cout << "Obj2(Obj2&&)\n";
+    }
+};
+
+int main()
+{
+    vector<int> v;
+
+    int nums = 20;
+    for (int i = 0; i < nums; ++i) {
+        v.push_back(i + 1);
+        cout << "v_size: " << v.size() << "\t v_capacity: " << v.capacity() << endl;
+    }
+    // 头两个在已有空间上成功构造。第三个时发现空间不足，系统会请求更大的空间，大小由实现决定（比如两倍）。
+    // 有了足够的空间后，就会在新空间的第三个的位置构造（第三个obj1），成功之后再把头两个拷贝或移动过来。
+    vector<Obj1> v1;
+//    v1.reserve(2);
+    v1.emplace_back();
+    v1.emplace_back();
+    v1.emplace_back();
+    v1.emplace_back();
+
+    vector<Obj2> v2;
+    v2.reserve(2);
+    v2.emplace_back();
+    v2.emplace_back();
+    v2.emplace_back();
+}