can someone explain this line for me ? :0

[xxgixxx]

explain the line underlined plz ?:0

std::ifstream fin;
fin.open("itemstore.dat",ios::binary);
fin.read((char*)&amt,sizeof(amt));

[AbstractionAnon]

Did you check the reference page?
http://www.cplusplus.com/reference/istream/istream/read/

You don't show the declaration of amt, so it's not clear whether that is an int, a double, a struct, or something else.

In any case, the statement takes the address of amt (whatever that is), casts it to a char pointer which is what read is expecting, passes the byte size of amt as the second argument, then calls read on the fin ifstream.