Doubly-linked list/Traversal: Difference between revisions
Added Algol W
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Line 199:
SALARY: +400
YEARS : +40
</pre>
=={{header|ALGOL W}}==
Using the element type and insertion routine from the Doubly Linked List/Eleemnt Insertion task.
<lang algolw>begin
% record type to hold an element of a doubly linked list of integers %
record DListIElement ( reference(DListIElement) prev
; integer iValue
; reference(DListIElement) next
);
% additional record types would be required for other element types %
% inserts a new element into the list, before e %
reference(DListIElement) procedure insertIntoDListIBefore( reference(DListIElement) value e
; integer value v
);
begin
reference(DListIElement) newElement;
newElement := DListIElement( null, v, e );
if e not = null then begin
% the element we are inserting before is not null %
reference(DListIElement) ePrev;
ePrev := prev(e);
prev(newElement) := ePrev;
prev(e) := newElement;
if ePrev not = null then next(ePrev) := newElement
end if_e_ne_null ;
newElement
end insertIntoDListiAfter ;
begin
reference(DListIElement) head, e, last;
head := null;
head := insertIntoDListIBefore( head, 1701 );
head := insertIntoDListIBefore( head, 9000 );
e := insertIntoDListIBefore( next(head), 90210 );
e := insertIntoDListIBefore( next(e), 4077 );
e := head;
last := null;
write( "Forward:" );
while e not = null do begin
write( i_w := 1, s_w := 0, " ", iValue(e) );
last := e;
e := next(e)
end while_e_ne_null ;
write( "Backward:" );
e := last;
while e not = null do begin
write( i_w := 1, s_w := 0, " ", iValue(e) );
last := e;
e := prev(e)
end while_e_ne_null
end
end.</lang>
{{out}}
<pre>
Forward:
9000
90210
4077
1701
Backward:
1701
4077
90210
9000
</pre>
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