finish cxx

a.cpp

@@ -0,0 +1,53 @@
+#include <iostream>
+#include <type_traits> // 用于检查类型
+#include <bits/stdc++.h> // 包含所有标准库头文件
+
+// 这是一个简单的帮助函数，用来告诉你一个值是左值还是右值
+void print_value_category(int& val) {
+    std::cout << "  -> 接收到一个【左值引用】" << std::endl;
+}
+
+void print_value_category(int&& val) {
+    std::cout << "  -> 接收到一个【右值引用】" << std::endl;
+}
+
+// 我们的模板函数，使用了 T&& 形参
+template <typename T>
+void inspect_param(T&& param) {
+    std::cout << "  在 inspect_param 内部，参数 param 的类型是: ";
+    // 注意：decltype(param) 会告诉你 param 变量本身的类型
+    // std::is_lvalue_reference 和 std::is_rvalue_reference 可以确认其引用类型
+    if (std::is_lvalue_reference<decltype(param)>::value) {
+        std::cout << "左值引用 (T&)";
+    } else if (std::is_rvalue_reference<decltype(param)>::value) {
+        std::cout << "右值引用 (T&&)";
+    } else {
+        std::cout << "值类型";
+    }
+    std::cout << "。\n";
+
+    // param 虽然类型可能是右值引用，但因为它有了名字，在函数内部它本身是【左值】
+    std::cout << "  现在把 param 传给 print_value_category：";
+    print_value_category(param); // 注意这里：直接传 param 总是传左值！
+}
+
+void example_reference_collapsing() {
+    std::cout << "--- 场景一：传入一个【右值】(字面量 10) ---" << std::endl;
+    inspect_param(10); // 传入一个右值字面量
+
+    std::cout << "\n--- 场景二：传入一个【左值】(变量 num) ---" << std::endl;
+    int num = 20; // num 是一个左值
+    inspect_param(num); // 传入一个左值变量
+}
+
+/*
+运行 example_reference_collapsing() 的输出会是这样：
+
+--- 场景一：传入一个【右值】(字面量 10) ---
+  在 inspect_param 内部，参数 param 的类型是: 右值引用 (T&&)。
+  现在把 param 传给 print_value_category：  -> 接收到一个【左值引用】
+
+--- 场景二：传入一个【左值】(变量 num) ---
+  在 inspect_param 内部，参数 param 的类型是: 左值引用 (T&)。
+  现在把 param 传给 print_value_category：  -> 接收到一个【左值引用】
+*/

exercises/00_hello_world/main.cpp

@@ -6,6 +6,6 @@
 
 int main(int argc, char **argv) {
     // TODO: 在控制台输出 "Hello, InfiniTensor!" 并换行
-    std::cout : "Hello, InfiniTensor!" + std::endl;
+    std::cout << "Hello, InfiniTensor!" << std::endl;
     return 0;
 }

exercises/01_variable&add/main.cpp

@@ -5,6 +5,7 @@
 int main(int argc, char **argv) {
     // TODO: 补全变量定义并打印加法运算
     // x ?
+    int x = 1;
     std::cout << x << " + " << x << " = " << x + x << std::endl;
     return 0;
 }

exercises/02_function/main.cpp

@@ -5,8 +5,9 @@
 // NOTICE: 补充由内而外读法的机翻解释 <https://learn.microsoft.com/zh-cn/cpp/c-language/interpreting-more-complex-declarators?view=msvc-170>
 
 // TODO: 在这里声明函数
-
+int add(int a, int b);
 int main(int argc, char **argv) {
+    // 断言add(123, 456)的返回值等于123 + 456
     ASSERT(add(123, 456) == 123 + 456, "add(123, 456) should be 123 + 456");
 
     auto x = 1, y = 2;
@@ -16,4 +17,5 @@ int main(int argc, char **argv) {
 
 int add(int a, int b) {
     // TODO: 补全函数定义，但不要移动代码行
+    return a + b;
 }

exercises/03_argument&parameter/main.cpp

@@ -8,19 +8,19 @@ void func(int);
 // TODO: 为下列 ASSERT 填写正确的值
 int main(int argc, char **argv) {
     auto arg = 99;
-    ASSERT(arg == ?, "arg should be ?");
+    ASSERT(arg == 99, "arg should be 99");
     std::cout << "befor func call: " << arg << std::endl;
     func(arg);
-    ASSERT(arg == ?, "arg should be ?");
+    ASSERT(arg == 99, "arg should be 99");
     std::cout << "after func call: " << arg << std::endl;
     return 0;
 }
 
 // TODO: 为下列 ASSERT 填写正确的值
 void func(int param) {
-    ASSERT(param == ?, "param should be ?");
+    ASSERT(param == 99, "param should be 99");
     std::cout << "befor add: " << param << std::endl;
     param += 1;
-    ASSERT(param == ?, "param should be ?");
+    ASSERT(param == 100, "param should be 100");
     std::cout << "after add: " << param << std::endl;
 }

exercises/04_static/main.cpp

@@ -4,16 +4,16 @@
 // THINK: 这个函数的两个 `static` 各自的作用是什么？
 static int func(int param) {
     static int static_ = param;
-    // std::cout << "static_ = " << static_ << std::endl;
+    std::cout << "static_ = " << static_ << std::endl;
     return static_++;
 }
 
 int main(int argc, char **argv) {
     // TODO: 将下列 `?` 替换为正确的数字
-    ASSERT(func(5) == ?, "static variable value incorrect");
-    ASSERT(func(4) == ?, "static variable value incorrect");
-    ASSERT(func(3) == ?, "static variable value incorrect");
-    ASSERT(func(2) == ?, "static variable value incorrect");
-    ASSERT(func(1) == ?, "static variable value incorrect");
+    ASSERT(func(5) == 5, "static variable value incorrect");
+    ASSERT(func(4) == 6, "static variable value incorrect");
+    ASSERT(func(3) == 7, "static variable value incorrect");
+    ASSERT(func(2) == 8, "static variable value incorrect");
+    ASSERT(func(1) == 9, "static variable value incorrect");
     return 0;
 }

exercises/05_constexpr/main.cpp

@@ -18,7 +18,7 @@ int main(int argc, char **argv) {
 
     // TODO: 观察错误信息，修改一处，使代码编译运行
     // PS: 编译运行，但是不一定能算出结果……
-    constexpr auto ANS_N = 90;
+    constexpr auto ANS_N = 30;
     constexpr auto ANS = fibonacci(ANS_N);
     std::cout << "fibonacci(" << ANS_N << ") = " << ANS << std::endl;
 

exercises/06_array/main.cpp

@@ -11,13 +11,13 @@ unsigned long long fibonacci(int i) {
             return 1;
         default:
             // TODO: 补全三目表达式缺失的部分
-            return <condition> ? <cache> : (arr[i] = fibonacci(i - 1) + fibonacci(i - 2));
+            return arr[i] ? arr[i] : (arr[i] = fibonacci(i - 1) + fibonacci(i - 2));
     }
 }
 
 int main(int argc, char **argv) {
     // TODO: 为此 ASSERT 填写正确的值
-    ASSERT(sizeof(arr) == ?, "sizeof array is size of all its elements");
+    ASSERT(sizeof(arr) == 90 * sizeof(unsigned long long), "sizeof array is size of all its elements");
     // ---- 不要修改以下代码 ----
     ASSERT(fibonacci(2) == 1, "fibonacci(2) should be 1");
     ASSERT(fibonacci(20) == 6765, "fibonacci(20) should be 6765");

exercises/07_loop/main.cpp

@@ -5,9 +5,9 @@
 // READ: 纯函数 <https://zh.wikipedia.org/wiki/%E7%BA%AF%E5%87%BD%E6%95%B0>
 static unsigned long long fibonacci(int i) {
     // TODO: 为缓存设置正确的初始值
-    static unsigned long long cache[96], cached;
+    static unsigned long long cache[96] = {0, 1}, cached = 2;
     // TODO: 设置正确的循环条件
-    for (; false; ++cached) {
+    for (; (int)cached <= i; ++cached) {
         cache[cached] = cache[cached - 1] + cache[cached - 2];
     }
     return cache[i];

exercises/08_pointer/main.cpp

@@ -5,6 +5,15 @@ bool is_fibonacci(int *ptr, int len, int stride) {
     ASSERT(len >= 3, "`len` should be at least 3");
     // TODO: 编写代码判断从 ptr 开始，每 stride 个元素取 1 个元素，组成长度为 n 的数列是否满足
     // arr[i + 2] = arr[i] + arr[i + 1]
+    for (int i = 2; i < len; i++) {
+        int* index1 = ptr + stride * (i - 2);
+        int* index2 = ptr + stride * (i - 1);
+        int* index3 = ptr + stride * i;
+        if (*index3 != *index1 + *index2) {
+            return false;
+        }
+
+    }
     return true;
 }
 

exercises/09_enum&union/main.cpp

@@ -37,7 +37,7 @@ ColorEnum convert_by_pun(Color c) {
 
     TypePun pun;
     // TODO: 补全类型双关转换
-
+    pun.c = c;
     return pun.e;
 }
 

exercises/10_trivial/main.cpp

@@ -3,14 +3,14 @@
 // READ: Trivial type <https://learn.microsoft.com/zh-cn/cpp/cpp/trivial-standard-layout-and-pod-types?view=msvc-170>
 
 struct FibonacciCache {
-    unsigned long long cache[16];
-    int cached;
+    unsigned long long cache[16] = {0, 1};
+    int cached = 2;
 };
 
 // TODO: 实现正确的缓存优化斐波那契计算
 static unsigned long long fibonacci(FibonacciCache &cache, int i) {
-    for (; false; ++cached) {
-        cache[cached] = cache[cached - 1] + cache[cached - 2];
+    for (; cache.cached <= i; ++cache.cached) {
+        cache.cache[cache.cached] = cache.cache[cache.cached - 1] + cache.cache[cache.cached - 2];
     }
     return cache.cache[i];
 }

exercises/11_method/main.cpp

@@ -1,12 +1,12 @@
 #include "../exercise.h"
 
 struct Fibonacci {
-    unsigned long long cache[128];
-    int cached;
+    unsigned long long cache[128] = {0, 1};
+    int cached = 2;
 
     // TODO: 实现正确的缓存优化斐波那契计算
     unsigned long long get(int i) {
-        for (; false; ++cached) {
+        for (; cached <= i; ++cached) {
             cache[cached] = cache[cached - 1] + cache[cached - 2];
         }
         return cache[i];

exercises/12_method_const/main.cpp

@@ -5,7 +5,8 @@
 struct Fibonacci {
     int numbers[11];
     // TODO: 修改方法签名和实现，使测试通过
-    int get(int i) {
+    int get(int i) const {
+        return numbers[i];
     }
 };
 

exercises/13_class/main.cpp

@@ -14,11 +14,15 @@ class Fibonacci {
 
 public:
     // TODO: 实现构造器
-    // Fibonacci()
+    Fibonacci() {
+        cache[0] = 0;
+        cache[1] = 1;
+        cached = 2;
+    }
 
     // TODO: 实现正确的缓存优化斐波那契计算
     size_t get(int i) {
-        for (; false; ++cached) {
+        for (; cached <= i; ++cached) {
             cache[cached] = cache[cached - 1] + cache[cached - 2];
         }
         return cache[i];

exercises/14_class_destruct/main.cpp

@@ -11,14 +11,17 @@ class DynFibonacci {
 
 public:
     // TODO: 实现动态设置容量的构造器
-    DynFibonacci(int capacity): cache(new ?), cached(?) {}
+    DynFibonacci(int capacity): cache(new size_t[capacity]), cached(2) {
+        cache[0] = 0;
+        cache[1] = 1;
+    }
 
     // TODO: 实现析构器，释放缓存空间
-    ~DynFibonacci();
+    ~DynFibonacci() = default;
 
     // TODO: 实现正确的缓存优化斐波那契计算
     size_t get(int i) {
-        for (; false; ++cached) {
+        for (; cached <= i; ++cached) {
             cache[cached] = cache[cached - 1] + cache[cached - 2];
         }
         return cache[i];

exercises/15_class_clone/main.cpp

@@ -10,17 +10,26 @@ class DynFibonacci {
 
 public:
     // TODO: 实现动态设置容量的构造器
-    DynFibonacci(int capacity): cache(new ?), cached(?) {}
+    DynFibonacci(int capacity): cache(new size_t[capacity]), cached(2) {
+        cache[0] = 0;
+        cache[1] = 1;
+    }
 
     // TODO: 实现复制构造器
-    DynFibonacci(DynFibonacci const &) = delete;
+    DynFibonacci(DynFibonacci const &T) {
+        this->cached = T.cached;
+        this->cache = new size_t[T.cached];
+        for (int i = 0; i < T.cached; ++i) {
+            this->cache[i] = T.cache[i];
+        }
+    }
 
     // TODO: 实现析构器，释放缓存空间
-    ~DynFibonacci();
+    ~DynFibonacci() = default;
 
     // TODO: 实现正确的缓存优化斐波那契计算
     size_t get(int i) {
-        for (; false; ++cached) {
+        for (; cached <= i; ++cached) {
             cache[cached] = cache[cached - 1] + cache[cached - 2];
         }
         return cache[i];

exercises/16_class_move/main.cpp

@@ -15,21 +15,44 @@ class DynFibonacci {
 
 public:
     // TODO: 实现动态设置容量的构造器
-    DynFibonacci(int capacity): cache(new ?), cached(?) {}
+    DynFibonacci(int capacity): cache(new size_t[capacity]), cached(2) {
+        cache[0] = 0;
+        cache[1] = 1;
+    }
 
     // TODO: 实现移动构造器
-    DynFibonacci(DynFibonacci &&) noexcept = delete;
+    DynFibonacci(DynFibonacci && T) noexcept {
+        cache = std::move(T.cache);
+        cached = std::move(T.cached);
+        delete[] T.cache;
+        T.cache = nullptr;
+        T.cached = 0;
+    }
 
     // TODO: 实现移动赋值
     // NOTICE: ⚠ 注意移动到自身问题 ⚠
-    DynFibonacci &operator=(DynFibonacci &&) noexcept = delete;
+    DynFibonacci &operator=(DynFibonacci && T) noexcept {
+        if (this == &T) {
+            return *this;
+        }
+        cache = std::move(T.cache);
+        cached = std::move(T.cached); 
+        delete[] T.cache;
+        T.cache = nullptr;
+        T.cached = 0;
+        return *this;
+    }
 
     // TODO: 实现析构器，释放缓存空间
-    ~DynFibonacci();
+    ~DynFibonacci() {
+        delete[] cache;
+        cache = nullptr;
+        cached = 0;
+    }
 
     // TODO: 实现正确的缓存优化斐波那契计算
     size_t operator[](int i) {
-        for (; false; ++cached) {
+        for (; cached <= i; ++cached) {
             cache[cached] = cache[cached - 1] + cache[cached - 2];
         }
         return cache[i];

exercises/17_class_derive/main.cpp

@@ -50,9 +50,9 @@ int main(int argc, char **argv) {
     B b = B(3);
 
     // TODO: 补全三个类型的大小
-    static_assert(sizeof(X) == ?, "There is an int in X");
-    static_assert(sizeof(A) == ?, "There is an int in A");
-    static_assert(sizeof(B) == ?, "B is an A with an X");
+    static_assert(sizeof(X) == sizeof(int), "There is an int in X");
+    static_assert(sizeof(A) == sizeof(int), "There is an int in A");
+    static_assert(sizeof(B) == sizeof(int) * 2, "B is an A with an X");
 
     i = 0;
     std::cout << std::endl