support bazel complie this project and format code.

practical_exercises/10_day_practice/day4/copy_ctor/BUILD

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+# please run `bazel run //practical_exercises/10_day_practice/day4/copy_ctor:clock`
+
+load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_library")
+
+cc_library(
+    name = "clock",
+    hdrs = ["clock.h"],
+)
+
+cc_binary(
+    name = "main",
+    srcs = ["clock.cpp"],
+    deps = [
+        ":clock",
+    ],
+)

practical_exercises/10_day_practice/day4/copy_ctor/clock.cpp

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+#include "clock.h"
+#include <iostream>
+using namespace std;
+Clock::Clock(int NewH, int NewM, int NewS) {
+  this->Hour = NewH;
+  this->Minute = NewM;
+  this->Second = NewS;
+}
+Clock::Clock(Clock &c) {
+  this->Hour = c.Hour;
+  this->Minute = c.Minute;
+  this->Second = c.Second;
+}
+void Clock::SetTime(int NewH, int NewM, int NewS) {
+  //加不加this指针都一样
+  this->Hour = NewH;
+  this->Minute = NewM;
+  this->Second = NewS;
+}
+void Clock::ShowTime() {
+  cout << this->Hour << endl;
+  cout << this->Minute << endl;
+  cout << this->Second << endl;
+}
+//析构函数
+Clock::~Clock() {}
+int main(int argc, char const *argv[]) {
+  Clock c(0, 0, 0);
+
+  c.SetTime(10, 20, 30);
+  c.ShowTime();
+  //拷贝构造函数调用
+  Clock c1(c);
+  c1.ShowTime();
+  c1.SetTime(90, 98, 99);
+  c1.ShowTime();
+  return 0;
+}

practical_exercises/10_day_practice/day4/copy_ctor/clock.h

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+#ifndef CLOCK
+#define CLOCK
+class Clock {
+public:
+  Clock(int NewH, int NewM, int NewS);
+  Clock(
+      Clock &
+          c); //拷贝构造函数,如果不加，编译器会自动生成一个拷贝构造函数，因此加不加都可以直接使用。
+  void SetTime(int NewH, int NewM, int NewS);
+  void ShowTime();
+  ~Clock(); //析构函数，编译器会自动产生一个默认的析构函数。
+private:
+  int Hour, Minute, Second;
+};
+
+#endif
+
+/*
+#ifndef   标识符
+       程序段1
+#else
+       程序段2
+#endif
+如果“标识符”未被定义过，则编译程序段1，否则编译程序段2。
+
+*/