关于指针形参的一点体会：
现在假设指针实参为地址&a(0001)在这个&a(0001)地址空间内所存储的是一个int类型的变量为0；
那么在被调用函数中，会临时开辟一个空间一片临时地址空间&b(0002)，在&b的所指向的地址空间内，其所存储的内容为
一个地址值，这个地址值，就是&a(0001).
所以现在在被调函数中，有两种变化的操作：
1. 对&b(0002)所指向的地址内存储的内容，进行改变，比如讲将&b(0002)所指向空间内的值就是(0001)改成0003，那么这个值的改变对
&a没有任何影响。
2. 对&b(0002),所指向的地址（0001）的所指向的内容，就是这个地址所存储的int类型的变量（原为0）进行改变，比如现在改为1，那么这将对&a的地址值，仍然是（0001），没有影响，但这改变其所指向的内容，将其改为了(int)1.
这就是，关于指针形参时候，所说的指针的指针的意思。
可以参考如下博客和代码：
参考 ：
http://blog.csdn.net/richerg85/article/details/14450183
http://www.cnblogs.com/lipeil/archive/2012/10/26/2740729.html
和：http://blog.sina.com.cn/s/blog_6ce6d0bf01016utv.html
关于指针形参的一点一点体会
```cpp
//============================================================================
// Name : TS.cpp
// Author : jiudianren
// Version :
// Copyright : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================
#include <iostream>
#include <functional>
using namespace std;
void swap(int *a,int *b)
{
int temp;
temp=*a;
*a=*b;
*b=temp;
cout<<"a=" <<a<<" ,"<<"b="<<b<<endl;
cout<<"*a=" <<*a<<" ,"<<"*b="<<*b<<endl;
cout<<"&a=" <<&a<<" ,"<<"&b="<<&b<<endl;
}
int main(){
int x=1;
int y=2;
cout<<"x=" <<x<<" ,"<<"y="<<y<<endl;
cout<<"&x=" <<&x<<" ,"<<"&y="<<&y<<endl;
swap(&x,&y);
cout<<"end:"<<endl;
cout<<"x=" <<x<<" ,"<<"y="<<y<<endl;
cout<<"&x=" <<&x<<" ,"<<"&y="<<&y<<endl;
}
```
-------------
输出
```
x=1 ,y=2
&x=0x28ff1c ,&y=0x28ff18
a=0x28ff1c ,b=0x28ff18
*a=2 ,*b=1
&a=0x28ff00 ,&b=0x28ff04
end:
x=2 ,y=1
&x=0x28ff1c ,&y=0x28ff18
```
#第二部分
```
//============================================================================
// Name : TS.cpp
// Author : jiudianren
// Version :
// Copyright : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================
#include <iostream>
#include <functional>
using namespace std;
int change(char* name){
cout<<"*******CHANGE--BEFORE******"<<endl;
cout<<"name=" <<name<<endl;
cout<<"*name=" <<*name<<endl;
cout<<"&name=" <<&name<<endl;
name="alter";
cout<<"*******CHANGE--AFTER********"<<endl;
cout<<"name=" <<name<<endl;
cout<<"*name=" <<*name<<endl;
cout<<"&name=" <<&name<<endl;
return 1;
}
int main()
{
char *str = "this is a test";
cout<<"******MAIN--BEFORE*****"<<endl;
cout<<"str=" <<str<<endl;
cout<<"&str=" <<&str<<endl;
change(str);
cout<<"*****MAIN--AFTER*****"<<endl;
cout<<"str=" <<str<<endl;
cout<<"&str=" <<&str<<endl;
return 1;
}
```
-------------
输出
```
******MAIN--BEFORE*****
str=this is a test
&str=0x28ff2c
*******CHANGE--BEFORE******
name=this is a test
*name=t
&name=0x28ff10
*******CHANGE--AFTER********
name=alter
*name=a
&name=0x28ff10
*****MAIN--AFTER*****
str=this is a test
&str=0x28ff2c
```
# 第三部分
```cpp
//============================================================================
// Name : TS.cpp
// Author : jiudianren
// Version :
// Copyright : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================
#include <iostream>
#include <functional>
#include <stdlib.h>
using namespace std;
#define PT 1
void my_malloc(void* * p, int size)
{
#if PT
cout<<"------func befor"<<endl;
cout<<"p : "<<p<<endl;
cout<<"*p: "<<*p<<endl;
cout<<"&p: "<<&p<<endl;
#endif
*p=malloc(sizeof(int)* size);
#if PT
cout<<"---------func after"<<endl;
cout<<"p: "<<p<<endl;
cout<<"*p: "<<*p<<endl;
cout<<"&p: "<<&p<<endl;
#endif
return ;
}
int main()
{
int temp=11;
int *a;
a=&temp;
#if PT
cout<<"---------main before"<<endl;
cout<<"a : "<<a<<endl;
cout<<"*a :"<<(int)*a<<endl;
cout<<"&a :"<<&a<<endl;
#endif
my_malloc((void ** )&a,10);
#if PT
cout<<"----------main after"<<endl;
cout<<"a: "<<a<<endl;
cout<<"*a: "<<*a<<endl;
cout<<"&a: "<<&a<<endl;
#endif
return 1;
}
```
输出
---------------
```
---------main before
a : 0x28ff2c
*a :11
&a :0x28ff28
------func befor
p : 0x28ff28
*p: 0x28ff2c
&p: 0x28ff10
---------func after
p: 0x28ff28
*p: 0x952ab8
&p: 0x28ff10
----------main after
a: 0x952ab8
*a: 9776208
&a: 0x28ff28
```
# 引用
```
void swapref(int &a,int &b)
{
cout << "******************before swapref:******************"<<endl;
cout<<"a=" <<a<<" ,"<<"b="<<b<<endl;
cout<<"&a=" <<&a<<" ,"<<"&b="<<&b<<endl;
int temp;
temp=a;
a=b;
b=temp;
cout << "******************after swapref:******************"<<endl;
cout<<"a=" <<a<<" ,"<<"b="<<b<<endl;
cout<<"&a=" <<&a<<" ,"<<"&b="<<&b<<endl;
}
int main(){
int x=1;
int y=2;
cout<<"******MAIN--BEFORE*****"<<endl;
cout<<"x=" <<x<<" ,"<<"y="<<y<<endl;
cout<<"&x=" <<&x<<" ,"<<"&y="<<&y<<endl;
//swap(&x,&y);
swapref(x, y);
cout<<"*****MAIN--AFTER*****"<<endl;
cout<<"x=" <<x<<" ,"<<"y="<<y<<endl;
cout<<"&x=" <<&x<<" ,"<<"&y="<<&y<<endl;
}
```
```
输出 ，待跑
```