C 指针的常见题 函数传参时的内存泄露

#include <iostream>

using namespace std;

void test(int* p)//void test(int* &p)
{
	cout<<"In the function;from main"<<endl;

	cout<<"Where is the p"<<endl;
	cout<<&p<<endl;

	cout<<"What's the p point to"<<endl;
	cout<<p<<endl;
	
	cout<<"p=new int[10]"<<endl;
	cout<<"What's the p point to now"<<endl;
	p=new int[10];
	cout<<p<<endl;

	cout<<"And the location of p is unchanged"<<endl;
	cout<<&p<<endl;
	cout<<"Out of the function ;return to main"<<endl;


}

int main()
{
	int *p=NULL;
	cout<<"Where is the p"<<endl;
	cout<<&p<<endl;

	cout<<"What's the p point to"<<endl;
	cout<<p<<endl;

	test(p);

	cout<<"What's the p point to now"<<endl;
	cout<<p<<endl;

	return 0;
}

Where is the p
0012FF28
What's the p point to
00000000
In the function;from main
Where is the p
0012FE54
What's the p point to
00000000
p=new int[10]
What's the p point to now
001E1AD0
And the location of p is unchanged
0012FE54
Out of the function ;return to main
What's the p point to now
00000000
请按任意键继续. . .

小结：
指针归根到底也是一个值，存放在栈中，有他自己的位置，他的值是指向内存的地址的。
就像这段代码，函数test的形参一开始指向的内存地址是main函数中p指向的地址。
至此，main函数中的p在test函数中没什么作用了，而test函数的作用仅仅是为形参p开辟空间，造成内存泄露。