Related blog post: C++ new research
1. Allocate space on the heap in C language, without calling construction and destruction:
The above code compiles will report an error!
Attach example code:
//小问学编程
#include<stdlib.h>
#include<string.h>
class CStudent{
public:
//构造函数
CStudent(){
printf("CStudent()\r\n");
};
//析构函数
~CStudent(){
printf("~CStudent()\r\n");
}
private:
int m_nStuID;//学号
};
int main()
{
//栈上的对象
//全局对象
//堆对象
char* pBuf=(char*)malloc(10);
CStudent* pStu=(CStudent*)malloc(sizeof(CStudent));
free(pStu);
return 0;
}
Two. C++
Attach example code:
//小问学编程
#include<iostream>
using namespace std;
//运算符：
//1.new 分配空间，调用构造函数
//2.delete 调用析构函数，释放空间
class CStudent{
public:
//构造函数
CStudent(){
cout<<"CStudent()\r\n";
};
//析构函数
~CStudent(){
cout<<"~CStudent()\r\n";
}
private:
int m_nStuID;//学号
};
int main()
{
//在堆上创建一个对象
CStudent* pStu=new CStudent;
if(pStu!=nullptr)
{
//释放对象
delete pStu;
}
return 0;
}
Ordinary basic data types can also use new and delete, but only to allocate memory space:
attach example code:
//小问学编程
#include<iostream>
using namespace std;
int main()
{
int* pN=new int;
delete pN;
return 0;
}
note:
1. When applying for an object on the heap, use new and delete instead of malloc and free.
2. Apply for an array on the heap in C language:
3. Apply for an array on the heap in C ++: new[] allocates an array, delete[] releases the array space, and must be used in conjunction (especially when applying for an object array).
Example:
4. The vs compiler will write the length of the current array in the first 4 bytes at the beginning of the heap when applying for an object array with new[] to record the number of destructuring calls when delete[] is released.