I have written perl and VB and this is my very first attept at C

there is a variable called name
which is a filename like somefile.ext

i want to check that name does not have the extention .mp3 or .rar or .ace (make it easy for me to add new types)
and if it is one of those extensions then it should do this

addreply(553, MSG_BAD_FILE_TYPE, name);
goto end;

a way to get whatever letters are after the last dot into a string would be useful