誕生日から年齢を計算(メモ)

一般的に計算する場合は下記計算式で。
(今日の日付-誕生日)/10000の小数点以下切捨て

PHP

echo (int)((20120423 - 19741029)/10000);

Perl

print int ((20120423 - 19741029)/10000);

Java

System.out.println( (int)((20120423 - 19741029)/10000) );

Perl

#!/usr/bin/perl
use strict;

my $byear = 1974;
my $bmon = 10;
my $bday = 29;
my ($day, $mon, $year) = (localtime(time))[3-5];

my $now = sprintf( "%04d%02d%02d", $year+1900, $mon+1, $day );
my $birth = sprintf( "%04d%02d%02d", $byear, $bmon, $bday );

my $age = int( ($now - $birth) / 10000 );
print $age, "\n";