# 内存分配与释放

主要是来讲一讲new与malloc的区别

首先要注意，new和malloc可以用来申请自定义的变量的内存，也可以用来申请类的内存

那么类是有构造函数和析构函数的

使用new的话，会自动调用构造函数，delete时会自动调用析构函数

使用malloc的话，就不会自动调用构造函数，delete时也不会自动调用析构函数

```cpp
int *ptr = new int;//单个对象分配
int *ptr = new int[10];//数组对象分配

delete ptr;      // 释放单个对象
ptr = nullptr;   // 避免悬挂指针

delete[] ptr;    // 释放数组对象
ptr = nullptr;   // 避免悬挂指针
```


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