Solution to Problem 1 (Fibonacci Sequence Problem)
program Fibonacci;
var
Fibonacci1, Fibonacci2 : integer;
temp : integer;
count : integer;
begin (* Main *)
writeln ('First ten Fibonacci
numbers are:');
count := 0;
Fibonacci1 := 0;
Fibonacci2 := 1;
repeat
write (Fibonacci2:7);
temp := Fibonacci2;
Fibonacci2 := Fibonacci1 +
Fibonacci2;
Fibonacci1 := Temp;
count := count + 1
until count = 10;
writeln;
(* Of course, you could use a FOR
loop or a WHILE loop
to solve this problem. *)
end. (* Main *)
|
Solution to Problem 2 (Powers of two problem)
program PowersofTwo;
const
numperline = 5;
maxnum = 20000;
base = 2;
var
number : longint;
linecount : integer;
begin (* Main *)
writeln ('Powers of ', base, ', 1
<= x <= ', maxnum, ':');
(* Set up for loop *)
number := 1;
linecount := 0;
(* Loop *)
while number <= maxnum do
begin
linecount := linecount + 1;
(* Print a comma and space
unless this is the first number on
the line *)
if linecount > 1 then
write (', ');
(* Display the number *)
write (number);
(* Print a comma and go to
the next line if this is the last
number on the line UNLESS it is the
last number of the series *)
if (linecount = numperline) and
not (number * 2 > maxnum) then
begin
writeln (',');
linecount := 0
end;
(* Increment number *)
number := number * base;
end; (* while *)
writeln;
(* This program can also be
written using a
REPEAT..UNTIL loop. *)
end. (* Main *)
|
Note that I used three constants: the base, the number of powers to
display on each line, and the maximum number. This ensures that the program
can be easily adaptable in the future.
Using constants rather than literals is a good programming habit to form.
When you write really long programs, you may refer to certain numbers
thousands of times. If you hardcoded them into your code, you'd have to
search them out. Also, you might use the same value in a different context,
so you can't simply do a global Search-and-Replace. Using a constant makes
it simpler to expand the program.
Also note that I used the longint type for the number
variable. This is because to fail the test number <= 20000, number
would have to reach 32768, the next power of two after 16384. This exceeds
the range of the integer type: -32768 to 32767. (try it without longint and
see what happens)
