need help on a code

i am writing a code on user account using c++ (console app). i wrote functions to take a newuser and one for and olduser. using a switch case i accept a user input of type int to specify either. the problem is that if the user accidentally inputs a character the jprogeram jams up. can anyone help me with a way to check whether the input is of correct data type,

the next is that i how do you make the characters for the passwords appear in a hidden format, like (mypassword)==(**********) on the screen when typing.