Meaning of (unsigned int) & amp; in C ++

Int main ()

{
Using namespace std;
Int I = 20;
Int m = (unsigned int) & I; // note the & Symbol
Cout <m <endl;
}

&: Indicates the meaning of the reference, indicating that m is an alias of I, which is equivalent to a small name of a person.

Let's look at the following example:

# Include

 
  
# Define FIND (struc, e) (int) & (struc *) 0)-> e) typedef struct {int a; char B [20]; double ccc ;} stu; int main () {printf ("% d \ n", FIND (stu, B [0]); printf ("% d \ n", FIND (stu, ccc); return 0 ;}

 

A macro FIND is defined here to FIND the offset between a variable in struc and struc.

(Struc *) 0 indicates to forcibly convert the constant 0 to the address pointed to by the struc * pointer;

& (Struc &) 0)-> e) indicates the address of e, a member of struc * 0.

Output result: 4 24