If you know a filename from a package which you want to install, you can use
apt-file utility to find package names.
apt-file searchs within both of the installed and not installed packages for files that you may need. For example if you want to find package name which contains
apt-file search stdio.h
If you're using the first time, apt-file needs to be index package contents with:
If you're not interested about package names which are not installed your system but you want to learn which packages provides your installed stdio.h file,
dpkg comes to help:
dpkg -S stdio.h