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

[tonnot]

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

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

struct inventory {
  char item[20];
  int quantity;
  double cost;
};


  for(int i=0; i<3; i++)
    fout.write((const char *) &inv[i], sizeof(inventory));

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[Lykurg]

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

[nish]

and arrays too.

[genjix]

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

[squidge]

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.

[wysota]

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

[franz]

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