Okay. I couldn't sleep until I corrected my error. This CMP sub works now!! Run the test and see it for yourself! Btw using vec() is not a mistake. If someone is trying to run UNICODE letters through this sub, then there's a serious error in the code, and it *should* fail. The programmer needs to test each string to make sure it contains nothing else but plain digits before trying to compare the two. Maybe I should include a line which converts a UNICODE string to plain ASCII string, but I don't know how to do that magic... :D
#!/usr/bin/perl w
use strict;
use warnings;
print CMP("0", $b);
print CMP("", $b);
print CMP("0", "");
print CMP("", "000");
print CMP("", "55");
print CMP("111", "55");
print CMP("8,000,021", "7,999,999");
print CMP("003", "1");
print CMP("001", "2");
print CMP("003", "11");
print CMP("54", "45");
print CMP("123", "32");
print CMP("5", "5");
print CMP("1222225", "001222225");
print CMP(" 15", "15");
print CMP("0010", "100");
print CMP("C97F", "C97E");
print CMP("2E", "AE");
print CMP("00101 ", "00101");
exit;
##################################################
# v2020.06.30
# Compares two large positive integers.
# The integers can be binary (ones and zeros),
# octal, decimal, or hexadecimal.
#
# NOTE: Both numbers must be in the same base.
# You shouldn't try to compare a binary number such
# as "10001101" to a hex number like "C4"
# as this will give a bad result.
#
# Returns: 0 if the numbers are equal
# 1 if the first one is greater
# 2 if the second one is greater
#
# Special cases:
# * When comparing an undefined value against
# an empty string or zero, they will be equal.
# * Minus signs are always ignored!
#
# Usage: INTEGER = CMP(STRING, STRING)
#
sub CMP
{
my $A = defined $_[0] ? uc($_[0]) : '';
my $B = defined $_[1] ? uc($_[1]) : '';
my $A2 = length($A);
my $B2 = length($B);
my ($A1, $B1, $CA, $CB, $DIFF) = (0, 0, 48, 48, 0);
# SHOW WHAT'S HAPPENING:
print "\n\nString1=$A\nString2=$B RET=";
# Find the first significant digit or starting pointer for each stri
+ng.
# We will call this A1 and B1. In case the string starts with zeros,
# spaces, tabs, new line characters,  and + signs, or other special
# characters, we skip through those. We ignore them.
while ($A1 < $A2 && vec($A, $A1, 8) < 49) { $A1++; }
while ($B1 < $B2 && vec($B, $B1, 8) < 49) { $B1++; }
# Find last significant digit or ending pointer for each string.
# We will call this A2 and B2.
while ($A2 > $A1 && vec($A, $A2, 8) < 48) {} $A2++;
while ($B2 > $B1 && vec($B, $B2, 8) < 48) {} $B2++;
# Calculate the number of digits in each number.
my $AL = $A2  $A1;
my $BL = $B2  $B1;
# Are both numbers the same length?
if ($AL == $BL)
{
# Compare from left to right, incrementing
# pointers A1 and B1 as we walk through all the digits.
while ($A1 < $A2)
{
$CA = vec($A, $A1++, 8); # Get digit from string A
$CB = vec($B, $B1++, 8); # Get digit from string B
$DIFF = $CA  $CB;
if ($DIFF) { return $DIFF < 0 ? 2 : 1; }
}
return 0;
}
return 1 if ($AL > $BL);
return 2 if ($AL < $BL);
return 0;
}
