It is often important to determine if a list is empty.  This can be done
in many ways, but only two are worth mentioning.  If either the lh_TailPred&
field is pointing to the list header or the ln_Succ& field of the node
lh_Head& is pointing to is zero, then the list is empty.

In code, for example, these methods would be written as follows:

    'You can use this method...
    IF PeekL&(list&, lh_TailPred&) = list& THEN PRINT "List is empty."

    'Or you can use this method
    IF PeekL&(PeekL&(list&, lh_Head&), ln_Succ&) = 0 THEN PRINT "List is empty."

Even if there is only one line of code required for this check, there is
a FUNCTION IsListEmpty& set up to do this check.  You should use it to
make your programs more readable.

For example:

    IF IsListEmpty&(list&) THEN PRINT "List is empty."

                                                     Back to List Functions