添加友元

base/CMakeLists.txt

@@ -75,4 +75,7 @@ add_executable(error3 exception/error3.cpp)
 add_executable(exc_mean exception/exc_mean.cpp)
 add_executable(error5 exception/error5.cpp)
 add_executable(newexcp exception/newexcp.cpp)
-add_executable(use_sales exception/use_sales.cpp)
+add_executable(use_sales exception/use_sales.cpp)
+add_executable(rtti1 exception/rtti1.cpp)
+add_executable(rtti2 exception/rtti2.cpp)
+add_executable(constcast exception/constcast.cpp)

base/exception/constcast.cpp

@@ -0,0 +1,27 @@
+//
+// Created by zhuyijun on 2021/9/15.
+//
+
+#include <iostream>
+
+using namespace std;
+
+void change(const int *pt, int n);
+
+int main() {
+
+    int pop1 = 38383;
+    const int pop2 = 2000;
+
+    cout << "pop1,pop2: " << pop1 << ", " << pop2 << endl;
+    change(&pop1, -103);
+    change(&pop2, -103);
+    cout << "pop1,pop2: " << pop1 << ", " << pop2 << endl;
+    return 0;
+}
+
+void change(const int *pt, int n) {
+    int *pc;
+    pc = const_cast<int *>(pt);
+    *pc += n;
+}

base/exception/rtti1.cpp

@@ -0,0 +1,85 @@
+//
+// Created by zhuyijun on 2021/9/14.
+//
+
+#include <iostream>
+#include <cstdlib>
+#include <ctime>
+
+using namespace std;
+
+class Grand {
+private:
+    int hold;
+public:
+    Grand(int h = 0) : hold(h) {}
+
+    virtual void Speak() const {
+        cout << "I am a grand class!\n";
+    }
+
+    virtual int Value() const {
+        return hold;
+    }
+};
+
+class Superb : public Grand {
+public:
+    Superb(int h = 0) : Grand(h) {}
+
+    void Speak() const {
+        cout << "I am a superb class!!\n";
+    }
+
+    virtual void Say() const {
+        cout << "I hold the superb value of" << Value() << "!\n";
+    }
+};
+
+class Magnificent : public Superb {
+private:
+    char ch;
+public:
+    Magnificent(int h = 0, char c = 'A') : Superb(h), ch(c) {}
+
+    void Speak() const {
+        cout << "I am a magnificent class!!\n";
+    }
+
+    void Say() const {
+        cout << "I hold the character " << ch << " and the integer " << Value() << "!\n";
+    }
+};
+
+Grand *GetOne();
+
+int main() {
+
+    srand(std::time(0));
+    Grand *pg;
+    Superb *ps;
+    for (int i = 0; i < 5; ++i) {
+        pg = GetOne();
+        pg->Speak();
+        if ((ps = dynamic_cast<Superb *>(pg))) {
+            ps->Say();
+        }
+    }
+    return 0;
+}
+
+Grand *GetOne() {
+    Grand *p;
+    switch (rand() % 3) {
+        case 0:
+            p = new Grand(rand() % 100);
+            break;
+        case 1:
+            p = new Superb(rand() % 100);
+            break;
+        case 2:
+            p = new Magnificent(rand() % 100, 'A' + rand() % 26);
+            break;
+    }
+    return p;
+}

base/exception/rtti2.cpp

@@ -0,0 +1,89 @@
+//
+// Created by zhuyijun on 2021/9/14.
+//
+
+#include <iostream>
+#include <cstdlib>
+#include <ctime>
+#include <typeinfo>
+using namespace std;
+
+class Grand {
+private:
+    int hold;
+public:
+    Grand(int h = 0) : hold(h) {}
+
+    virtual void Speak() const {
+        cout << "I am a grand class!\n";
+    }
+
+    virtual int Value() const {
+        return hold;
+    }
+};
+
+class Superb : public Grand {
+public:
+    Superb(int h = 0) : Grand(h) {}
+
+    void Speak() const {
+        cout << "I am a superb class!!\n";
+    }
+
+    virtual void Say() const {
+        cout << "I hold the superb value of" << Value() << "!\n";
+    }
+};
+
+class Magnificent : public Superb {
+private:
+    char ch;
+public:
+    Magnificent(int h = 0, char c = 'A') : Superb(h), ch(c) {}
+
+    void Speak() const {
+        cout << "I am a magnificent class!!\n";
+    }
+
+    void Say() const {
+        cout << "I hold the character " << ch << " and the integer " << Value() << "!\n";
+    }
+};
+
+Grand *GetOne();
+
+int main() {
+
+    srand(time(0));
+    Grand *pg;
+    Superb *ps;
+    for (int i = 0; i < 5; ++i) {
+        pg = GetOne();
+        cout <<"Now processing type "<< typeid(*pg).name() <<".\n";
+        pg->Speak();
+        if ((ps = dynamic_cast<Superb *>(pg))) {
+            ps->Say();
+        }
+        if (typeid(Magnificent) == typeid(*pg)){
+            cout <<"Yes, you're really magnificent.\n";
+        }
+    }
+    return 0;
+}
+
+Grand *GetOne() {
+    Grand *p;
+    switch (rand() % 3) {
+        case 0:
+            p = new Grand(rand() % 100);
+            break;
+        case 1:
+            p = new Superb(rand() % 100);
+            break;
+        case 2:
+            p = new Magnificent(rand() % 100, 'A' + rand() % 26);
+            break;
+    }
+    return p;
+}