Object-oriented Software in Ada 95

106 Arrays
procedure Add_To(The:in out Histogram; A_Ch:in Character) is
Ch : Character;
begin
Ch := A_Ch;
--As write to ch
if Is_Lower(Ch) then --Convert to upper case
Ch := To_Upper( Ch );
end if;
if Is_Upper( Ch ) then --so record
declare
C : Alphabet_Index := Alphabet_Index(Ch);
begin
The.Number_Of(C) := The.Number_Of(C) + 1;
end;
end if;
end Add_To;
The histogram is displayed as a bar graph corresponding to the accuracy of the output device, which in this case is
an ANSI terminal. The size of the histogram is set by the defaulted parameter Height.
procedure Put(The:in Histogram;
Height:in Positive:=Def_Height) is
Frequency : Alphabet_Array; --Copy to process
Max_Height : Natural := 0; --Observed max
begin
Frequency := The.Number_Of; --Copy data (Array)
for Ch in Alphabet_Array'Range loop --Find max frequency
if Frequency(Ch) > Max_Height then
Max_Height:= Frequency(Ch);
end if;
end loop;
if Max_Height > 0 then
for Ch in Alphabet_Array'Range loop --Scale to max height
Frequency(Ch):=(Frequency(Ch)*Height)/(Max_Height);
end loop;
end if;
for Row in reverse 1 .. Height loop --Each line
Put( " | " );
--start of line
for Ch in Alphabet_Array'Range loop
if Frequency(Ch) >= Row then
Put('*');
--bar of hist >= col
else
Put(' ');
--bar of hist < col
end if;
end loop;
Put(" | "); New_Line; --end of line
end loop;
Put(" +----------------------------+"); New_Line;
Put(" ABCDEFGHIJKLMNOPQRSTUVWXYZ " ); New_Line;
Put(" * = (approx) ");
Put( Float(Max_Height) / Float(Height), Aft=>2, Exp=>0 );
Put(" characters "); New_Line;
end Put;
end Class_Histogram;
Note:
By implementing the printing of the histogram as part of the package Class_Histogram this
severely limits the cases when this code can be re-used.
© M A Smith - May not be reproduced without permission