Can anybody explain me this 'kind of casting'¿?

I have found this code to write data:
inv is an 'inventory' array.
I dont undertad he line that writes data, it makes some casting but ....
Can anybody help me ? ( I dont understand (const char*) neither & for inv.
thanks

Code:

---

struct inventory {
  char item[20];
  int quantity;
  double cost;
};
 
 
  for(int i=0; i<3; i++)
    fout.write((const char *) &inv[i], sizeof(inventory));

---

It all about basic C++. Read about explicit casting and pointers/references.

and arrays too.

Isn't that pretty bad code since struct padding might change the binary file between systems? I think you should not use that code.

Its true that struct padding might change the structure size, but if your only interested in one system (or the file is only written/read on one system, eg. an internal data file) then its fine. It just means more work later on if you want the make the files portable between different architectures/systems.

And possibly some garbage (possibly containing some sensitive data) written to the file.

Always pack your structs if they are going to leave the program...