revision #1: 更新第二章中已维护的代码

code/1/1.1.c.and.cpp

@@ -2,7 +2,7 @@
 // 1.1.cpp
 //
 // chapter 1 introduction
-// c++1x tutorial
+// modern cpp tutorial
 //
 // created by changkun at changkun.de
 //
@@ -12,7 +12,7 @@
 #include <functional>
 
 int main() {
-    // 使用 lambda 表达式
+    // use lambda expression
     [out = std::ref(std::cout << "Result from C code: " << add(1, 2))](){
         out.get() << ".\n";
     }();

code/1/Makefile

@@ -2,21 +2,21 @@
 # 1.1.cpp
 #
 # chapter 1 introduction
-# c++1x tutorial
+# modern cpp tutorial
 #
 # created by changkun at changkun.de
 #
 
 C = gcc
-CXX = g++
+CXX = clang++
 
 SOURCE_C = foo.c
 OBJECTS_C = foo.o 
 
-SOURCE_CXX = 1.1.cpp
+SOURCE_CXX = 1.1.c.and.cpp
 
-TARGET = 1.1
-LDFLAGS_COMMON = -std=c++1z
+TARGET = 1.1.out
+LDFLAGS_COMMON = -std=c++17
 
 all:
 	$(C) -c $(SOURCE_C)

code/1/foo.c

@@ -2,14 +2,14 @@
 // foo.c
 //
 // chapter 1 introduction
-// c++1x tutorial
+// modern cpp tutorial
 //
 // created by changkun at changkun.de
 //
 
 #include "foo.h"
 
-// C 语言代码
+// C code
 int add(int x, int y) {
     return x+y;
 }

code/1/foo.h

@@ -2,7 +2,7 @@
 // foo.h
 //
 // chapter 1 introduction
-// c++1x tutorial
+// modern cpp tutorial
 //
 // created by changkun at changkun.de
 //

code/2/2.1.cpp

@@ -1,32 +0,0 @@
-//
-// 2.1.cpp
-// c++1x tutorial
-//
-// created by changkun at changkun.de
-//
-// nullptr
-
-#include <iostream>
-
-void foo(char *);
-void foo(int);
-
-int main() {
-    
-    if(NULL == (void *)0)
-        std::cout << "NULL == 0" << std::endl;  // 该行将输出
-    else
-        std::cout << "NULL != 0" << std::endl;
-    
-    foo(0);         // 调用 foo(int)
-    //foo(NULL);    // 该行不能通过编译
-    foo(nullptr);   // 调用 foo(char*)
-    
-    return 0;
-}
-void foo(char *ch) {
-    std::cout << "call foo(char*)" << std::endl;
-}
-void foo(int i) {
-    std::cout << "call foo(int)" << std::endl;
-}

code/2/2.1.nullptr.cpp

@@ -0,0 +1,34 @@
+//
+// 2.1.nullptr.cpp
+// chapter 2 language usability
+// modern cpp tutorial
+//
+// created by changkun at changkun.de
+//
+
+#include <iostream>
+#include <type_traits>
+
+void foo(char *);
+void foo(int);
+
+int main() {
+    if (std::is_same<decltype(NULL), decltype(0)>::value)
+        std::cout << "NULL == 0" << std::endl;
+    if (std::is_same<decltype(NULL), decltype((void*)0)>::value)
+        std::cout << "NULL == (void *)0" << std::endl;
+    if (std::is_same<decltype(NULL), std::nullptr_t>::value)
+        std::cout << "NULL == nullptr" << std::endl;
+
+    foo(0);          // will call foo(int)
+    // foo(NULL);    // doen't compile
+    foo(nullptr);    // will call foo(char*)
+    return 0;
+}
+
+void foo(char *) {
+    std::cout << "foo(char*) is called" << std::endl;
+}
+void foo(int i) {
+    std::cout << "foo(int) is called" << std::endl;
+}

code/2/2.10.if.constexpr.cpp

@@ -0,0 +1,31 @@
+//
+// 2.10.if.constexpr.cpp
+// chapter 2 language usability
+// modern cpp tutorial
+//
+// created by changkun at changkun.de
+//
+
+#include <iostream>
+
+template<typename T>
+auto print_type_info(const T& t) {
+    if constexpr (std::is_integral<T>::value) {
+        return t + 1;
+    } else {
+        return t + 0.001;
+    }
+}
+
+// at compiling time
+// int print_type_info(const int& t) {
+//     return t + 1;
+// }
+// double print_type_info(const double& t) {
+//     return t + 0.001;
+// }
+
+int main() {
+    std::cout << print_type_info(5) << std::endl;
+    std::cout << print_type_info(3.14) << std::endl;
+}

code/2/2.11.for.loop.cpp

@@ -0,0 +1,23 @@
+//
+// 2.11.for.loop.cpp
+// chapter 2 language usability
+// modern cpp tutorial
+//
+// created by changkun at changkun.de
+//
+
+#include <iostream>
+#include <vector>
+#include <algorithm>
+
+int main() {
+    std::vector<int> vec = {1, 2, 3, 4};
+    if (auto itr = std::find(vec.begin(), vec.end(), 3); itr != vec.end()) *itr = 4;
+    for (auto element : vec)
+        std::cout << element << std::endl; // read only
+    for (auto &element : vec) {
+        element += 1;                      // writeable
+    }
+    for (auto element : vec)
+        std::cout << element << std::endl; // read only
+}

code/2/2.2.constexpr.cpp

@@ -0,0 +1,50 @@
+//
+// 2.2.constexpr.cpp
+// chapter 2 language usability
+// modern cpp tutorial
+//
+// created by changkun at changkun.de
+//
+
+#include <iostream>
+#define LEN 10
+
+int len_foo() {
+    int i = 2;
+    return i;
+}
+constexpr int len_foo_constexpr() {
+    return 5;
+}
+
+// error in c++11
+// constexpr int fibonacci(const int n) {
+//     if(n == 1) return 1;
+//     if(n == 2) return 1;
+//     return fibonacci(n-1) + fibonacci(n-2);
+// }
+
+// ok
+constexpr int fibonacci(const int n) {
+    return n == 1 || n == 2 ? 1 : fibonacci(n-1) + fibonacci(n-2);
+}
+
+
+int main() {
+    char arr_1[10];                      // legal
+    char arr_2[LEN];                     // legal
+
+    int len = 10;
+    // char arr_3[len];                  // illegal
+
+    const int len_2 = len + 1;
+    char arr_4[len_2];                   // legal
+
+    // char arr_5[len_foo()+5];          // illegal
+    char arr_6[len_foo_constexpr() + 1]; // legal
+    
+    // 1, 1, 2, 3, 5, 8, 13, 21, 34, 55
+    std::cout << fibonacci(10) << std::endl;
+
+    return 0;
+}

code/2/2.2.cpp

@@ -1,34 +0,0 @@
-//
-// 2.2.cpp
-// c++1x tutorial
-//
-// created by changkun at changkun.de
-//
-// constexpr
-
-#include <iostream>
-#define LEN 10
-
-constexpr int len_foo() {
-    return 5;
-}
-
-constexpr int fibonacci(const int n) {
-    return n == 1 || n == 2 ? 1 : fibonacci(n-1)+fibonacci(n-2);
-}
-
-int main() {
-    char arr_1[10];
-    
-    char arr_2[LEN];
-    
-    const int len = 10;
-    char arr_3[len];
-    
-    char arr_5[len_foo()+5];
-    
-    std::cout << fibonacci(10) << std::endl;
-    // 1, 1, 2, 3, 5, 8, 13, 21, 34, 55
-    
-    return 0;
-}

code/2/2.3.if.switch.cpp

@@ -0,0 +1,31 @@
+//
+// 2.3.if.switch.cpp
+// chapter 2 language usability
+// modern cpp tutorial
+//
+// created by changkun at changkun.de
+//
+
+#include <iostream>
+#include <vector>
+#include <algorithm>
+
+int main() {
+    std::vector<int> vec = {1, 2, 3, 4};
+
+    // before c++17, can be simplefied by using `auto`
+    const std::vector<int>::iterator itr = std::find(vec.begin(), vec.end(), 2);
+    if (itr != vec.end()) {
+        *itr = 3;
+    }
+
+    // after c++17, can be simplefied by using `auto`
+    if (const std::vector<int>::iterator itr = std::find(vec.begin(), vec.end(), 3);
+        itr != vec.end()) {
+        *itr = 4;
+    }
+
+    // should output: 1, 4, 3, 4. can be simplefied using `auto`
+    for (std::vector<int>::iterator element = vec.begin(); element != vec.end(); ++element)
+        std::cout << *element << std::endl;
+}

code/2/2.4.initializer.list.cpp

@@ -0,0 +1,59 @@
+//
+// 2.4.initializer.list.cpp
+// chapter 2 language usability
+// modern cpp tutorial
+//
+// created by changkun at changkun.de
+//
+
+#include <iostream>
+#include <initializer_list>
+#include <vector>
+
+class Foo {
+public:
+    int value_a;
+    int value_b;
+    Foo(int a, int b) : value_a(a), value_b(b) {}
+};
+
+class MagicFoo {
+public:
+    std::vector<int> vec;
+    MagicFoo(std::initializer_list<int> list) {
+        for (std::initializer_list<int>::iterator it = list.begin(); it != list.end(); ++it) {
+            vec.push_back(*it);
+        }
+    }
+    void foo(std::initializer_list<int> list) {
+        for (std::initializer_list<int>::iterator it = list.begin(); it != list.end(); ++it) {
+            vec.push_back(*it);
+        }
+    }
+};
+
+int main() {
+    // before C++11
+    int arr[3] = {1, 2, 3};
+    Foo foo(1, 2);
+    std::vector<int> vec = {1, 2, 3, 4, 5};
+
+    // after C++11
+    MagicFoo magicFoo = {1, 2, 3, 4, 5};
+    magicFoo.foo({6,7,8,9});
+    Foo foo2 {3, 4};
+
+    std::cout << "arr[0]: " << arr[0] << std::endl;
+    std::cout << "foo:" << foo.value_a << ", " << foo.value_b << std::endl;
+    std::cout << "vec: ";
+    for (std::vector<int>::iterator it = vec.begin(); it != vec.end(); ++it) {
+        std::cout << *it << std::endl;
+    }
+    std::cout << "magicFoo: ";
+    for (std::vector<int>::iterator it = magicFoo.vec.begin(); it != magicFoo.vec.end(); ++it) {
+        std::cout << *it << std::endl;
+    }
+    std::cout << "foo2: " << foo2.value_a << ", " << foo2.value_b << std::endl;
+
+    return 0;
+}

code/2/2.5.cpp

@@ -1,34 +0,0 @@
-//
-// 2.5.cpp
-// c++1x tutorial
-//
-// created by changkun at changkun.de
-//
-// 初始化列表
-
-
-#include <initializer_list>
-
-class Foo {
-private:
-    int value;
-public:
-    Foo(int) {}
-};
-
-class Magic {
-public:
-    Magic(std::initializer_list<int> list) {}
-};
-
-void func(std::initializer_list<int> list) {
-    return;
-}
-
-int main() {
-    int arr[3] = {1,2,3};       // 列表初始化
-    Foo foo(1);                 // 普通构造初始化
-    
-    Magic magic = {1,2,3,4,5};  // 使用 initialize_list
-    func({1,2,3});
-}

code/2/2.5.structured.binding.cpp

@@ -0,0 +1,20 @@
+//
+// 2.5.structured.binding.cpp
+// chapter 2 language usability
+// modern cpp tutorial
+//
+// created by changkun at changkun.de
+//
+
+#include <iostream>
+#include <string>
+
+std::tuple<int, double, std::string> f() {
+    return std::make_tuple(1, 2.3, "456");
+}
+
+int main() {
+    auto [x, y, z] = f();
+    std::cout << x << ", " << y << ", " << z << std::endl;
+    return 0;
+}

code/2/2.6.auto.cpp

@@ -0,0 +1,42 @@
+//
+// 2.6.auto.cpp
+// chapter 2 language usability
+// modern cpp tutorial
+//
+// created by changkun at changkun.de
+//
+
+#include <initializer_list>
+#include <vector>
+#include <iostream>
+
+class MagicFoo {
+public:
+    std::vector<int> vec;
+    MagicFoo(std::initializer_list<int> list) {
+        for (auto it = list.begin(); it != list.end(); ++it) {
+            vec.push_back(*it);
+        }
+    }
+};
+
+// wrong
+// int add(auto x, auto y) {
+//     return x+y;
+// }
+
+int main() {
+    MagicFoo magicFoo = {1, 2, 3, 4, 5};
+    std::cout << "magicFoo: ";
+    for (auto it = magicFoo.vec.begin(); it != magicFoo.vec.end(); ++it) {
+        std::cout << *it << ", ";
+    }
+    std::cout << std::endl;
+
+    auto i = 5;                 // type int
+    auto j = 6;                 // type int
+    auto arr = new auto(10);    // type int*
+    // auto auto_arr2[10] = arr;
+    // std::cout << add(i, j) << std::endl;
+    return 0;
+}

code/2/2.7.decltype.cpp

@@ -0,0 +1,23 @@
+//
+// 2.7.decltype.cpp
+// chapter 2 language usability
+// modern cpp tutorial
+//
+// created by changkun at changkun.de
+//
+
+#include <iostream>
+#include <type_traits>
+
+int main() {
+    auto x = 1;
+    auto y = 2;
+    decltype(x+y) z = 3;
+    if (std::is_same<decltype(x), int>::value)
+        std::cout << "type x == int" << std::endl;
+    if (std::is_same<decltype(x), float>::value)
+        std::cout << "type z == float" << std::endl;
+    if (std::is_same<decltype(x), decltype(z)>::value)
+        std::cout << "type z == type x" << std::endl;
+    return 0;
+}

code/2/2.8.tail.return.type.cpp

@@ -0,0 +1,46 @@
+//
+// 2.8.tail.return.type.cpp
+// chapter 2 language usability
+// modern cpp tutorial
+//
+// created by changkun at changkun.de
+//
+
+#include <iostream>
+#include <type_traits>
+
+// before c++11
+template<typename R, typename T, typename U>
+R add(T x, U y) {
+    return x + y;
+}
+// after c++11
+template<typename T, typename U>
+auto add2(T x, U y) -> decltype(x+y){
+    return x + y;
+}
+// after c++14
+template<typename T, typename U>
+auto add3(T x, U y){
+    return x + y;
+}
+
+int main() {
+
+    // before c++11
+    int z = add<int, int, int>(1, 2);
+    std::cout << z << std::endl;
+
+    // after c++11
+    auto w = add2<int, double>(1, 2.0);
+    if (std::is_same<decltype(w), double>::value) {
+        std::cout << "w is double: ";
+    }
+    std::cout << w << std::endl;
+
+    // after c++14
+    auto q = add3<double, int>(1.0, 2);
+    std::cout << "q: " << q << std::endl;
+
+    return 0;
+}

code/2/2.9.decltype.auto.cpp

@@ -0,0 +1,21 @@
+//
+// 2.9.decltype.auto.cpp
+// chapter 2 language usability
+// modern cpp tutorial
+//
+// created by changkun at changkun.de
+//
+
+template<int i>
+struct Int {};
+
+constexpr auto iter(Int<0>) -> Int<0>;
+
+template<int i>
+constexpr auto iter(Int<i>) {
+    return iter(Int<i-1>{});
+}
+
+int main() {
+    decltype(iter(Int<10>{})) a;
+}

code/2/Makefile

@@ -0,0 +1,7 @@
+all: $(patsubst %.cpp, %.out, $(wildcard *.cpp))
+
+%.out: %.cpp Makefile
+	clang++ $< -o $@ -std=c++17
+
+clean:
+	rm *.out

code/2/todo/2.6.autox.cpp

@@ -32,7 +32,7 @@ int main() {
     
     int arr[10] = {0};
     auto auto_arr = arr;        // 正确，对整个类型进行推导
-    //auto auto_arr2[10] = arr; // 错误,  无法推导数组元素类型
+    // auto auto_arr2[10] = arr;   // 错误,  无法推导数组元素类型
 
     auto x = 1;
     auto y = 2;

code/2/todo/2.xxx.cpp

@@ -0,0 +1,21 @@
+#include <iostream>
+
+template<typename T0>
+void printf(T0 value) {
+    std::cout << value << std::endl;
+}
+template<typename T, typename... Args>
+void printf(T value, Args... args) {
+    std::cout << value << std::endl;
+    printf(args...);
+}
+
+template<typename T0, typename... T>
+void printf_short(T0 t0, T... t) {
+    std::cout << t0 << std::endl;
+    if constexpr (sizeof...(t) > 0) printf(t...);
+}
+int main() {
+    printf_short(1, 2, "123", 1.1);
+    return 0;
+}

code/2/todo/fold.expression.cpp

@@ -0,0 +1,8 @@
+#include <iostream>
+template<typename ... T>
+auto sum(T ... t) {
+    return (t + ...);
+}
+int main() {
+    std::cout << sum(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) << std::endl;
+}