Say I have the user input a zipcode, and it turns out to be something like 00020. And then I want to display it to the user. How do I have it so that it displays 00020 and not 20?

you would be better off declaring it as a char, your other option would be to use an int array to hold each value individually. but a char makes the most sense for a zip code.

cout << setw( 5 ) << setfill( '0' ) << zipcode;