* vs &


 
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# 1  
Old 10-02-2002
* vs &

what's the difference between *(pointer) and &(reference)? sometime i see code use * and sometime it uses &, i'm comfuse as when to use which.
thanks.
# 2  
Old 10-02-2002
They are the reverse of each other. The ampersand gives you an address of an object. The star uses an address stored in an object.
Code:
int i, *p;
i=5;   /* i is now 5 */
p=&i;  /* the address of i is now stored in p */
*p=6;  /* i is now 6 but p did not change */

# 3  
Old 10-09-2002
Re: * vs &

Quote:
Originally posted by bb00y
what's the difference between *(pointer) and &(reference)? sometime i see code use * and sometime it uses &, i'm comfuse as when to use which.
thanks.
& is also used in "pass by reference" in C++ (not C). Works like pointers but some people may consider easier to work with by reference instead of pointers:

Code:
#include <stdio.h>
void add(int &a, int b) {
   // adds a and b, and put result to
   // variable referenced by "a"
   a += b;
}
int main(int argc, char** argv) {
   int myval = 4;
   // myval references to "a" in add(), so a change
   // to either one modifies the same variable
   add(myval, 6);
   printf("%d\n", myval);    // should be 10
   return 0;
}


Last edited by cbkihong; 10-10-2002 at 12:26 AM..
# 4  
Old 10-31-2002
just a few pointers.. (Smilie)

Unlike pointers, you must immediately initialize a reference:

Quote:
int a = 5;
int* ptr; // OK!
int& x; // Error!
int& y = a; // OK!
Also remember that you can't use an operator to operate on the reference like you can do with pointers. An example...


Quote:
#include <iostream>
using std::cout;
using std::endl;

int main()
{
&nbsp; &nbsp; int a[4] = {12, 8, 543, 74};
&nbsp; &nbsp; int* ptr = &a[2];
&nbsp; &nbsp; int& ref = a[2];

&nbsp; &nbsp; ptr++;
&nbsp; &nbsp; ref++;&nbsp; &nbsp; //Nothing happens to the reference

&nbsp; &nbsp; cout << "reference: " << ref << endl;
&nbsp; &nbsp; cout << "pointer: " << *ptr << endl;
}
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