new和delete的使用
最后更新于：2022-04-02 02:07:38
[TOC]
## 基本数据类型的动态分配
using namespace std;
int main()
{
//基本数据类型
int *i1=new int;
int *i2=new int();
int *i3=new int(100);
float *i4=new float(1.11f);
cout << "i1 = " <<*i1 << endl;
cout << "i2 = " <<*i2 << endl;
cout << "i3 = " <<*i3 << endl;
cout << "i4 = " <<*i4 << endl;
//数组
int *iArr = new int[3];
for (size_t i = 0; i < 3; i++)
{
iArr[i]=i;
cout << i << " : " << iArr[i] << endl;
}
// 释放内存
delete i1;
delete i2;
delete i3;
delete i4;
delete []iArr;
return 0 ;
}
```
## 内存分配时的出错处理
using namespace std;
int main()
{
//判断指针是否为NULL
double *arr1 = new double[100000];
if (!arr1)
{
cout << "内存分配出错！" << endl;
return 1;
}
delete[] arr1;
// try catch
try
{
double *arr2 = new double[100000];
delete[] arr2;
}
catch (const std::exception &e)
{
std::cerr << "内存分配出错！" << endl;
return 1;
}
double *arr3 = new (nothrow) double[100000];
if (!arr3)
{
cout << "内存分配出错！" << endl;
return 1;
}
delete[] arr3;
cout << "内存分配成功！" << endl;
return 0;
}
```
## 用new产生类的实例
using namespace std;
class A
{
public:
int x;
void setX(int x)
{
this->x = x;
}
int getX()
{
return this->x;
}
};
int main()
{
A *a = new A();
if (!a)
{
cout << "内存分配出错！" << endl;
return 1;
}
a->setX(123);
cout << a->getX() << endl;
delete a;
return 0;
}
```
';
main.cpp
``` #include## 内存分配时的出错处理
main.cpp
``` #include## 用new产生类的实例