Hours calculation

Question

I need to calculate the exact time that a given record has to be analyzed.

Each registration has a intermission where it can be analysed and, a maximum value in hours, referring to deadline for analysis.

Example

End time = Registration date + Deadline = 26/12/2014 04:24:31

But I need the off-hours to be ignored, which means:

• The day 25 would be counted only 01:35:29, because the interval is until 22h
• It would return the count from 08h, finalizing the exact time 26/12/2014 14:24:31

My current solution is a loop for each record:

$incremento = 0
$cadastro = "26/12/2014 04:24:31"
$intervalo_inicial = 8
$intervalo_final = 10
$prazo = 8

while ($incremento <> $prazo) {
    if ($cadastro >= $intervalo_inicial) and ($cadastro <= $intervalo_final) {
        $incremento += 1
    }
    // adiciona 1 hora
    $cadastro = date($cadastro, strtotime('1 hour'));
}

However, calculating 100,000 record makes the task very slow. Any type of solution is valid, database, formula, logic..

Answer 1

You can use division to know how many full days you used and how many hours left.

To avoid confusion in this example (due to two different values worth 8), I changed the deadline to 7 hours. Also, in the version actually I would use the minimum unit of time count to do the math (seconds or milliseconds, depends on what you are using) but in the example I represented everything using hours to be clearer.

$tempo_inicio = 20:24:31 - 08:00:00  // = 12:24:31
$prazo = 07:00:00
$tempo_fim = $hora_inicio + $prazo // = 19:24:31

$horas_por_dia = 22:00:00 - 08:00:00 // = 14:00:00

// quociente e resto da divisão
$dias_gastos = $tempo_fim / $horas_por_dia  // 1
$horas_ultimo_dia = $tempo_fim % $horas_por_dia // 5:24:31

$dia_fim = $dia_inicio + $dias_gastos // dia 26
$hora_fim = 8:00:00 + $horas_ultimo_dia // 13:24:31