program ThousandSeparatorSpaces;
{$mode objfpc}{$H+}
uses
SysUtils;
{
Program: Print numbers with a thousand separator as spaces in Free Pascal.
Architecture notes:
-------------------
- Free Pascal does not provide built-in thousand-separator formatting.
- We implement a manual formatter:
* Convert the number to a string.
* Handle negative numbers cleanly.
* Insert spaces every three digits from the left.
- The function is modular, reusable, and efficient.
Performance notes:
------------------
- O(n) time where n is the number of digits.
- Memory usage is minimal; only small strings are created.
- No external libraries; uses only standard Free Pascal features.
Pitfalls:
---------
- Must preserve the minus sign for negative numbers.
- Must ensure correct grouping even for very large integers.
- Avoid formatting floating-point values unless converted to integers first.
Security notes:
---------------
- No external input parsing; safe for demonstration.
- Avoid printing sensitive values in real systems.
Tests:
------
- Positive numbers
- Negative numbers
- Zero
- Very large integers
}
function FormatWithSpaces(n: Int64): string;
var
s, digits: string;
isNegative: boolean;
lenDigits, firstGroup, i, pos: integer;
begin
s := IntToStr(n);
isNegative := (s[1] = '-');
if isNegative then
digits := Copy(s, 2, Length(s) - 1)
else
digits := s;
lenDigits := Length(digits);
{ Determine how many digits before the first space }
firstGroup := lenDigits mod 3;
if firstGroup = 0 then
firstGroup := 3;
Result := '';
{ Add minus sign if needed }
if isNegative then
Result := '-';
{ Add first group }
Result := Result + Copy(digits, 1, firstGroup);
{ Add remaining groups of 3 digits }
pos := firstGroup + 1;
while pos <= lenDigits do
begin
Result := Result + ' ' + Copy(digits, pos, 3);
pos := pos + 3;
end;
end;
procedure RunTests;
var
tests: array[1..6] of Int64;
i: integer;
begin
tests[1] := 0;
tests[2] := 42;
tests[3] := 1234;
tests[4] := 987654321;
tests[5] := -1234567;
tests[6] := 1000000000000000000; { 10^18 }
Writeln('Running test cases:');
Writeln;
for i := 1 to Length(tests) do
begin
Writeln('Original: ', tests[i]);
Writeln('Formatted: ', FormatWithSpaces(tests[i]));
Writeln;
end;
end;
begin
RunTests;
end.
{
run:
Running test cases:
Original: 0
Formatted: 0
Original: 42
Formatted: 42
Original: 1234
Formatted: 1 234
Original: 987654321
Formatted: 987 654 321
Original: -1234567
Formatted: -1 234 567
Original: 1000000000000000000
Formatted: 1 000 000 000 000 000 000
}
