dc: Miscellaneous

1 
1 10 Miscellaneous
1 ****************
1 
1 '!'
1      Will run the rest of the line as a system command.  Note that
1      parsing of the !<, !=, and !> commands take precedence, so if you
1      want to run a command starting with <, =, or > you will need to add
1      a space after the !.
1 
1 '#'
1      Will interpret the rest of the line as a comment.  (This command is
1      a GNU extension.)
1 
1 ':R'
1      Will pop the top two values off of the stack.  The old
1      second-to-top value will be stored in the array R, indexed by the
1      old top-of-stack value.
1 
1 ';R'
1      Pops the top-of-stack and uses it as an index into the array R.
1      The selected value is then pushed onto the stack.
1 
1    Note that each stacked instance of a register has its own array
1 associated with it.  Thus '1 0:A 0SA 2 0:A LA 0;Ap' will print 1,
1 because the 2 was stored in an instance of 0:A that was later popped.
1