History variables: Difference between revisions
Added Algol W
(Added Rust) |
(Added Algol W) |
||
Line 189:
<pre>one oneone three
14</pre>
=={{header|ALGOL W}}==
Algol W does not have history variables as standard, as with other languages here, we can add them using a simple linked list.
<br>As Algol W does not have generic types, a separate history variable type would be required for each type of variable.
<lang algolw>begin
% implements integer history variables %
% similar history types could be defined for other types of variable %
record HInteger ( integer iValue; reference(HInteger) iPrev );
% sets the latest value of hv to n %
procedure setIhv ( reference(HInteger) value result hv; integer value n ) ; hv := HInteger( n, hv );
% declare an integer history variable %
reference(HInteger) hv;
% initialise the history to a null value %
hv := null;
% assign three values %
setIhv( hv, 1 );
setIhv( hv, 2 );
setIhv( hv, 3 );
% show the history of hv %
begin
reference(HInteger) h;
write( "hv history: " );
h := hv;
while h not = null do begin
writeon( i_w := 3, s_w := 0, iValue(h), " " );
h := iPrev(h)
end while_h_ne_null
end;
% remove the values from hv, summing them as in the Ada sample %
begin
integer s;
s := 0;
while hv not = null do begin
s := s + iValue(hv);
hv := iPrev(hv)
end while_hv_ne_null ;
write( "Sum of the historic values: ", s )
end
end.</lang>
{{out}}
<pre>
hv history: 3 2 1
Sum of the historic values: 6
</pre>
=={{header|AspectJ}}==
| |||