# Question about using pointer with reference

• December 7th, 2010, 11:39 AM
lordelf2004
Question about using pointer with reference
Hi everyone!

I have problems in using pointer with reference. So, I make simple program to clarify them.

First of all, this is my code and its output. Please notice line (*) and (**):

My code:
//////////////////////////////////////////////////////////////////////////////////////////
void RefFunc(int*& a){
int q = 888;
a = &q; //PROPLEM HERE (*) - //*a = q
cout << "address of a after assign= " << &a << endl;
cout << "value of a after assign= " << *a << endl;
}
int main ()
{
int * ptr;
int p = 777;
ptr = &p;
RefFunc((int*&)ptr); //PROPLEM HERE(**) - ptr
cout << "address of ptr after RefFunc function = " << &ptr << endl;
cout << "value of ptr after RefFunc function = " << *ptr << endl;
getch();
return 0;
}
//////////////////////////////////////////////////////////////////////////////////////////
Output:
address of a after assign = 0012FF28
value of a after assign = 888
address of ptr after RefFunc function = 0012FF28
value of ptr after RefFunc function = 1730693832
//////////////////////////////////////////////////////////////////////////////////////////

These are what I tried:
1- I think "value of ptr after RefFunc function" should be the same with the value of variable 'a' in RefFunc because I use pointer - reference (*&) in RefFunc function. But it is not...(see the output)

2- When I modified line (*) to "*a = q": this time, "value of ptr after RefFunc function" is the same with 'a' in RefFunc (888).

3- In line (**) - I used RefFunc((int*&)ptr) or RefFunc(ptr): these two ways have the same results to output.

Anyone can explain for me the difference between:

1- <a = &q> and <*a = q> in line (*) in this situation, why *ptr does not change its value when I use <a = &q> whereas it does when I used <*a = q>?

2- <RefFunc((int*&)ptr)> and <RefFunc(ptr)>: what does it means in this case?

• December 7th, 2010, 01:10 PM
Paul McKenzie
Re: Question about using pointer with reference
Quote:

Originally Posted by lordelf2004
Hi everyone!

I have problems in using pointer with reference.

How is this related to the Windows API? You should post in the non-Visual C++ forum, not this one.

Regards,

Paul McKenzie
• December 7th, 2010, 01:18 PM
lordelf2004
Re: Question about using pointer with reference
Thanks Paul McKenzie ,

I have reposted to http://www.codeguru.com/forum/showth...25#post1985125