# 拷贝运算符和赋值运算符

以下是拷贝构造函数被调用的几种常见情况：

1. **直接初始化**： 当通过现有对象初始化新对象时，拷贝构造函数被调用。

   ```cpp
   MyClass obj1;
   MyClass obj2 = obj1; // 调用拷贝构造函数
   ```
2. **按值传递对象**： 当对象按值传递给函数时，拷贝构造函数被调用。

   ```cpp
   void func(MyClass obj) {
       // 拷贝构造函数被调用
   }

   int main() {
       MyClass obj;
       func(obj); // 传值调用函数，触发拷贝构造函数
   }
   ```
3. **按值返回对象**： 当函数按值返回对象时，拷贝构造函数被调用。不过，现代编译器通常会通过返回值优化（RVO）来避免实际的拷贝操作。

   ```cpp
   MyClass createObject() {
       MyClass obj;
       return obj; // 可能调用拷贝构造函数
   }

   int main() {
       MyClass obj = createObject(); // 可能调用拷贝构造函数
   }
   ```


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