Can you write the results of the commands below? I think there is still a problem about installation..
Code:
[mbaris@slackware:~]$ which gcc
/usr/bin/gcc
[mbaris@slackware:~]$ which cc
/usr/bin/cc
[mbaris@slackware:~]$ ls -l /usr/bin/cc
lrwxrwxrwx 1 root root 3 May 18 01:07 /usr/bin/cc -> gcc
[mbaris@slackware:~]$
Also, AFAIK,
rpm -qi gcc should give the package information if it's installed. These outputs may help..