Can anyone tell me about these lines that why we use them in our program during filehandling process..Thanks in advance.. :)

int pos=(-1)*static_cast<int>(sizeof(account))

Having just one line to look out a complete answer is impossible but the line of code gets the size of the account object, uses the static_cast method to convert it to an int (which it was already but is probably used to avoid any unsafe type issues).
Then it's multiplied by -1 and stored in the pos variable.
So, basically, it is the negative size of the account object.

What happens with it then is anyone's guess.

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