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practical_exercises/10_day_practice/day7/一元运算符/秒钟自增运算.cpp

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+//设计一个时间类Time，它能够完成秒钟的自增运算。
+
+#include<iostream>
+using namespace std;
+
+class Time{
+    private:
+        int hour,minute,second;
+    public:
+        Time(int h,int m, int s);
+        Time operator++();
+        //友元重载需要参数
+        friend Time operator--(Time &t);
+        void display(); 
+};
+
+Time::Time(int h, int m, int s){
+    hour=h;
+    minute=m;
+    second=s;
+    if (hour>=24)
+        hour=0;
+    if (minute>=60)
+        minute=0;
+    if (second>=60)
+        second=0;
+}
+
+Time Time::operator++(){
+    ++second;
+    if (second>=60){
+        second=0;
+        ++minute;
+        if(minute>=60){
+            minute=0;
+            ++hour;
+            if(hour>=24)
+                hour=0;
+        }
+    }
+    return *this;       
+}
+Time operator--(Time &t){
+    --t.second;
+    if (t.second>=60){
+        t.second=0;
+        ++t.minute;
+        if(t.minute>=60){
+            t.minute=0;
+            ++t.hour;
+            if(t.hour>=24)
+                t.hour=0;
+        }
+    }
+    return t;  
+}
+void Time::display(){
+    cout<<hour<<":"<<minute<<":"<<second<<endl;
+}
+int main(int argc, char const *argv[])
+{
+    Time t1(23,59,59);
+    t1.display();
+    ++t1; //隐式调用
+    t1.display();
+    t1.operator++(); //显式调用
+    t1.display();
+    Time t2(24,60,60);
+    t2.display();
+    ++t2;
+    t2.display();
+    --t2;
+    t2.display();
+    system("pause");
+    return 0;
+}

practical_exercises/10_day_practice/day7/一元运算符/计数器前后自增.cpp

@@ -0,0 +1,47 @@
+//设计一个计数器counter，用类成员重载自增运算符实现计数器的自增，用友元重载实现计数器的自减。
+#include<iostream>
+using namespace std;
+class Counter{
+    private:
+        int n;
+    public:
+        Counter(int i=0):n(i){};
+        Counter operator++();
+        Counter operator++(int);
+        friend Counter operator--(Counter &c);
+        friend Counter operator--(Counter &c,int);
+        void display();
+};
+Counter Counter::operator++(){
+    ++n;
+    return *this;
+}
+Counter Counter::operator++(int){
+    n++;
+    return *this;
+}
+Counter operator--(Counter &c){
+    --c.n;
+    return c;
+}
+Counter operator--(Counter &c,int){
+    c.n--;
+    return c;
+}
+void Counter::display(){
+    cout<<"counter number="<<n<<endl;
+}
+int main(int argc, char const *argv[])
+{
+    Counter a;
+    ++a;
+    a.display();
+    a++;
+    a.display();
+    --a;
+    a.display();
+    a--;
+    a.display();
+    system("pause");
+    return 0;
+}