Calcular os dias úteis

Obter o número de dias úteis sem férias entre duas datas:

Usar o exemplo:

echo number_of_working_days('2013-12-23', '2013-12-29');

Resultado:

3

Função:

function number_of_working_days($from, $to) {
    $workingDays = [1, 2, 3, 4, 5]; # date format = N (1 = Monday, ...)
    $holidayDays = ['*-12-25', '*-01-01', '2013-12-23']; # variable and fixed holidays

    $from = new DateTime($from);
    $to = new DateTime($to);
    $to->modify('+1 day');
    $interval = new DateInterval('P1D');
    $periods = new DatePeriod($from, $interval, $to);

    $days = 0;
    foreach ($periods as $period) {
        if (!in_array($period->format('N'), $workingDays)) continue;
        if (in_array($period->format('Y-m-d'), $holidayDays)) continue;
        if (in_array($period->format('*-m-d'), $holidayDays)) continue;
        $days++;
    }
    return $days;
}

Existem alguns args para a função data() que devem ajudar. Se você verificar a data ("w") ele lhe dará um número para o dia da semana, de 0 para domingo a 6 para sábado. Entao.. talvez algo do género..

$busDays = 3;
$day = date("w");
if( $day > 2 && $day <= 5 ) { /* if between Wed and Fri */
  $day += 2; /* add 2 more days for weekend */
}
$day += $busDays;

Este é apenas um exemplo áspero de uma possibilidade..

/**
 * National American Holidays
 * @param string $year
 * @return array
 */
public static function getNationalAmericanHolidays($year) {


    //  January 1 - New Year’s Day (Observed)
    //  Calc Last Monday in May - Memorial Day  strtotime("last Monday of May 2011");
    //  July 4 Independence Day
    //  First monday in september - Labor Day strtotime("first Monday of September 2011")
    //  November 11 - Veterans’ Day (Observed)
    //  Fourth Thursday in November Thanksgiving strtotime("fourth Thursday of November 2011");
    //  December 25 - Christmas Day        
    $bankHolidays = array(
          $year . "-01-01" // New Years
        , "". date("Y-m-d",strtotime("last Monday of May " . $year) ) // Memorial Day
        , $year . "-07-04" // Independence Day (corrected)
        , "". date("Y-m-d",strtotime("first Monday of September " . $year) ) // Labor Day
        , $year . "-11-11" // Veterans Day
        , "". date("Y-m-d",strtotime("fourth Thursday of November " . $year) ) // Thanksgiving
        , $year . "-12-25" // XMAS
        );

    return $bankHolidays;
}

Aqui está uma função para adicionar dias de buissness a uma data

 function add_business_days($startdate,$buisnessdays,$holidays,$dateformat){
  $i=1;
  $dayx = strtotime($startdate);
  while($i < $buisnessdays){
   $day = date('N',$dayx);
   $date = date('Y-m-d',$dayx);
   if($day < 6 && !in_array($date,$holidays))$i++;
   $dayx = strtotime($date.' +1 day');
  }
  return date($dateformat,$dayx);
 }

 //Example
 date_default_timezone_set('Europe\London');
 $startdate = '2012-01-08';
 $holidays=array("2012-01-10");
 echo '<p>Start date: '.date('r',strtotime( $startdate));
 echo '<p>'.add_business_days($startdate,7,$holidays,'r');

Usando o seguinte (terá de incluir a função getWorkingDays do post anterior)

 date_default_timezone_set('Europe\London');
 //Example:
 $holidays = array('2012-01-10');
 $startDate = '2012-01-08';
 $endDate = '2012-01-13';
 echo getWorkingDays( $startDate,$endDate,$holidays);

Dá o resultado como 5 não 4

Sun, 08 Jan 2012 00:00:00 +0000 weekend
Mon, 09 Jan 2012 00:00:00 +0000
Tue, 10 Jan 2012 00:00:00 +0000 holiday
Wed, 11 Jan 2012 00:00:00 +0000
Thu, 12 Jan 2012 00:00:00 +0000
Fri, 13 Jan 2012 00:00:00 +0000 

A seguinte função foi usada para gerar a acima.

     function get_working_days($startDate,$endDate,$holidays){
      $debug = true;
      $work = 0;
      $nowork = 0;
      $dayx = strtotime($startDate);
      $endx = strtotime($endDate);
      if($debug){
       echo '<h1>get_working_days</h1>';
       echo 'startDate: '.date('r',strtotime( $startDate)).'<br>';
       echo 'endDate: '.date('r',strtotime( $endDate)).'<br>';
       var_dump($holidays);
       echo '<p>Go to work...';
      }
      while($dayx <= $endx){
       $day = date('N',$dayx);
       $date = date('Y-m-d',$dayx);
       if($debug)echo '<br />'.date('r',$dayx).' ';
       if($day > 5 || in_array($date,$holidays)){
        $nowork++;
     if($debug){
      if($day > 5)echo 'weekend';
      else echo 'holiday';
     }
       } else $work++;
       $dayx = strtotime($date.' +1 day');
      }
      if($debug){
      echo '<p>No work: '.$nowork.'<br>';
      echo 'Work: '.$work.'<br>';
      echo 'Work + no work: '.($nowork+$work).'<br>';
      echo 'All seconds / seconds in a day: '.floatval(strtotime($endDate)-strtotime($startDate))/floatval(24*60*60);
      }
      return $work;
     }

    date_default_timezone_set('Europe\London');
     //Example:
     $holidays=array("2012-01-10");
     $startDate = '2012-01-08';
     $endDate = '2012-01-13';
//broken
     echo getWorkingDays( $startDate,$endDate,$holidays);
//works
     echo get_working_days( $startDate,$endDate,$holidays);

$startDate = new DateTime( '2013-04-01' );    //intialize start date
$endDate = new DateTime( '2013-04-30' );    //initialize end date
$holiday = array('2013-04-11','2013-04-25');  //this is assumed list of holiday
$interval = new DateInterval('P1D');    // set the interval as 1 day
$daterange = new DatePeriod($startDate, $interval ,$endDate);
foreach($daterange as $date){
if($date->format("N") <6 AND !in_array($date->format("Y-m-d"),$holiday))
$result[] = $date->format("Y-m-d");
}
echo "<pre>";print_r($result);

Uma função para adicionar ou subtrair dias úteis a partir de uma dada data, isto não conta para férias.

function dateFromBusinessDays($days, $dateTime=null) {
  $dateTime = is_null($dateTime) ? time() : $dateTime;
  $_day = 0;
  $_direction = $days == 0 ? 0 : intval($days/abs($days));
  $_day_value = (60 * 60 * 24);

  while($_day !== $days) {
    $dateTime += $_direction * $_day_value;

    $_day_w = date("w", $dateTime);
    if ($_day_w > 0 && $_day_w < 6) {
      $_day += $_direction * 1; 
    }
  }

  return $dateTime;
}

Usa assim...

echo date("m/d/Y", dateFromBusinessDays(-7));
echo date("m/d/Y", dateFromBusinessDays(3, time() + 3*60*60*24));

function business_days_add($start_date, $business_days, $holidays = array()) {
    $current_date = strtotime($start_date);
    $business_days = intval($business_days); // Decrement does not work on strings
    while ($business_days > 0) {
        if (date('N', $current_date) < 6 && !in_array(date('Y-m-d', $current_date), $holidays)) {
            $business_days--;
        }
        if ($business_days > 0) {
            $current_date = strtotime('+1 day', $current_date);
        }
    }
    return $current_date;
}

E determinar a diferença de duas datas em termos de dias úteis:

function business_days_diff($start_date, $end_date, $holidays = array()) {
    $business_days = 0;
    $current_date = strtotime($start_date);
    $end_date = strtotime($end_date);
    while ($current_date <= $end_date) {
        if (date('N', $current_date) < 6 && !in_array(date('Y-m-d', $current_date), $holidays)) {
            $business_days++;
        }
        if ($current_date <= $end_date) {
            $current_date = strtotime('+1 day', $current_date);
        }
    }
    return $business_days;
}

Como nota, todos os que usam 86400, ou 24*60*60 por favor, não... seu tempo de esquecimento muda a partir do inverno / verão, onde um dia não é exatamente 24 horas. Enquanto é um pouco mais devagar o strtotime ('+1 dia', $timestamp), é muito mais confiável.

if (date('N')<6 && date('G')>8 && date('G')<16) {
   // we have a working time (or check for holidays)
}

Você pode tentar esta função que é mais simples.

function getWorkingDays($startDate, $endDate)
{
    $begin = strtotime($startDate);
    $end   = strtotime($endDate);
    if ($begin > $end) {

        return 0;
    } else {
        $no_days  = 0;
        while ($begin <= $end) {
            $what_day = date("N", $begin);
            if (!in_array($what_day, [6,7]) ) // 6 and 7 are weekend
                $no_days++;
            $begin += 86400; // +1 day
        };

        return $no_days;
    }
}

Para as férias, faça uma série de dias em algum formato que a data() pode produzir. Exemplo:

// I know, these aren't holidays
$holidays = array(
    'Jan 2',
    'Feb 3',
    'Mar 5',
    'Apr 7',
    // ...
);

Utilize então as funções in_array() e date() para verificar se a data representa um feriado:

$day_of_year = date('M j', $timestamp);
$is_holiday = in_array($day_of_year, $holidays);

  function add_business_days($startdate,$buisnessdays,$holidays=array(),$dateformat){
    $enddate = strtotime($startdate);
    $day = date('N',$enddate);
    while($buisnessdays > 1){
        $enddate = strtotime(date('Y-m-d',$enddate).' +1 day');
        $day = date('N',$enddate);
        if($day < 6 && !in_array($enddate,$holidays))$buisnessdays--;
    }
    return date($dateformat,$enddate);
  }

Com alguém

Variante 1:

<?php
/*
 * Does not count current day, the date returned is the last business day
 * Requires PHP 5.1 (Using ISO-8601 week)
 */

function businessDays($timestamp = false, $bDays = 2) {
    if($timestamp === false) $timestamp = time();
    while ($bDays>0) {
        $timestamp += 86400;
        if (date('N', $timestamp)<6) $bDays--;
    }
    return $timestamp;
}

Variante 2:

<?php
/*
 * Does not count current day, the date returned is a business day 
 * following the last business day
 * Requires PHP 5.1 (Using ISO-8601 week)
 */

function businessDays($timestamp = false, $bDays = 2) {
    if($timestamp === false) $timestamp = time();
    while ($bDays+1>0) {
        $timestamp += 86400;
        if (date('N', $timestamp)<6) $bDays--;
    }
    return $timestamp;
}

Variante 3:

<?php
/*
 * Does not count current day, the date returned is 
 * a date following the last business day (can be weekend or not. 
 * See above for alternatives)
 * Requires PHP 5.1 (Using ISO-8601 week)
 */

function businessDays($timestamp = false, $bDays = 2) {
    if($timestamp === false) $timestamp = time();
    while ($bDays>0) {
        $timestamp += 86400;
        if (date('N', $timestamp)<6) $bDays--;
    }
    return $timestamp += 86400;
}

As considerações adicionais de férias podem ser feitas usando variações do acima fazendo o seguinte. Nota! assegurar que todos os horários são a mesma hora do dia (ou seja, meia-noite).

Fazer um conjunto de datas de férias (como datas não fixadas) ou seja:

$holidays = array_flip(strtotime('2011-01-01'),strtotime('2011-12-25'));

Modificar a linha:

if (date('N', $timestamp)<6) $bDays--;

A ser:

if (date('N', $timestamp)<6 && !isset($holidays[$timestamp])) $bDays--;

<?php
/*
 * Does not count current day, the date returned is the last business day
 * Requires PHP 5.1 (Using ISO-8601 week)
 */

function businessDays($timestamp = false, $bDays = 2) {
    if($timestamp === false) $timestamp = strtotime(date('Y-m-d',time()));
    $holidays = array_flip(strtotime('2011-01-01'),strtotime('2011-12-25'));
    while ($bDays>0) {
        $timestamp += 86400;
        if (date('N', $timestamp)<6 && !isset($holidays[$timestamp])) $bDays--;
    }
    return $timestamp;
}

<?php 
function AddWorkDays(){
$i = 0;
$d = 5; // Number of days to add

    while($i <= $d) {
    $i++;
        if(date('N', mktime(0, 0, 0, date(m), date(d)+$i, date(Y))) < 5) {
            $d++;
        }
    }
    return date(Y).','.date(m).','.(date(d)+$d);
}
?>

//  Returns a $numBusDays-sized array of all business dates, 
//  starting from and including $currentDate. 
//  Any date in $holidays will be skipped over.

function getWorkingDays($currentDate, $numBusDays, $holidays = array(), 
  $resultDates = array())
{
  //  exit when we have collected the required number of business days
  if ($numBusDays === 0) {
    return $resultDates;
  }

  //  add current date to return array, if not a weekend or holiday
  $date = date("w", strtotime($currentDate));
  if ( $date != 0  &&  $date != 6  &&  !in_array($currentDate, $holidays) ) {
    $resultDates[] = $currentDate;
    $numBusDays -= 1;
  }

  //  set up the next date to test
  $currentDate = new DateTime("$currentDate + 1 day");
  $currentDate = $currentDate->format('Y-m-d');

  return getWorkingDays($currentDate, $numBusDays, $holidays, $resultDates);
}

//  test
$days = getWorkingDays('2008-12-05', 4);
print_r($days);

date_default_timezone_set('America/New_York');


/** Given a number days out, what day is that when counting by 'business' days
  * get the next business day. by default it looks for next business day
  * ie calling  $date = get_next_busines_day(); on monday will return tuesday
  *             $date = get_next_busines_day(2); on monday will return wednesday
  *             $date = get_next_busines_day(2); on friday will return tuesday
  *
  * @param $number_of_business_days (integer)       how many business days out do you want
  * @param $start_date (string)                     strtotime parseable time value
  * @param $ignore_holidays (boolean)               true/false to ignore holidays
  * @param $return_format (string)                  as specified in php.net/date
 */
function get_next_business_day($number_of_business_days=1,$start_date='today',$ignore_holidays=false,$return_format='m/d/y') {

    // get the start date as a string to time
    $result = strtotime($start_date);

    // now keep adding to today's date until number of business days is 0 and we land on a business day
    while ($number_of_business_days > 0) {
        // add one day to the start date
        $result = strtotime(date('Y-m-d',$result) . " + 1 day");

        // this day counts if it's a weekend and not a holiday, or if we choose to ignore holidays
        if (is_weekday(date('Y-m-d',$result)) && (!(is_holiday(date('Y-m-d',$result))) || $ignore_holidays) ) 
            $number_of_business_days--;

    }

    // when my $number of business days is exausted I have my final date

    return(date($return_format,$result));
}

    function is_weekend($date) {
    // return if this is a weekend date or not.
    return (date('N', strtotime($date)) >= 6);
}

function is_weekday($date) {
    // return if this is a weekend date or not.
    return (date('N', strtotime($date)) < 6);
}

function is_holiday($date) {
    // return if this is a holiday or not.

    // what are my holidays for this year
    $holidays = array("New Year's Day 2011" => "12/31/10",
                        "Good Friday" => "04/06/12",
                        "Memorial Day" => "05/28/12",
                        "Independence Day" => "07/04/12",
                        "Floating Holiday" => "12/31/12",
                        "Labor Day" => "09/03/12",
                        "Thanksgiving Day" => "11/22/12",
                        "Day After Thanksgiving Day" => "11/23/12",
                        "Christmas Eve" => "12/24/12",
                        "Christmas Day" => "12/25/12",
                        "New Year's Day 2012" => "01/02/12",
                        "New Year's Day 2013" => "01/01/13"
                        );

    return(in_array(date('m/d/y', strtotime($date)),$holidays));
}


print get_next_business_day(1) . "\n";

<?php
// $today is the UNIX timestamp for today's date
$today = time();
echo "<strong>Today is (ORDER DATE): " . '<font color="red">' . date('l, F j, Y', $today) . "</font></strong><br/><br/>";

//The numerical representation for day of week (Ex. 01 for Monday .... 07 for Sunday
$today_numerical = date("N",$today);

//leadtime_days holds the numeric value for the number of business days 
$leadtime_days = $_POST["leadtime"];

//leadtime is the adjusted date for shipdate
$shipdate = time();

while ($leadtime_days > 0) 
{
 if ($today_numerical != 5 && $today_numerical != 6)
 {
  $shipdate = $shipdate + (60*60*24);
  $today_numerical = date("N",$shipdate);
  $leadtime_days --;
 }
 else
  $shipdate = $shipdate + (60*60*24);
  $today_numerical = date("N",$shipdate);
}

echo '<strong>Estimated Ship date: ' . '<font color="green">' . date('l, F j, Y', $shipdate) . "</font></strong>";
?>

Segue-se o código de trabalho para calcular os dias úteis a partir de uma determinada data.

<?php
$holiday_date_array = array("2016-01-26", "2016-03-07", "2016-03-24", "2016-03-25", "2016-04-15", "2016-08-15", "2016-09-12", "2016-10-11", "2016-10-31");
$date_required = "2016-03-01";

function increase_date($date_required, $holiday_date_array=array(), $days = 15){
    if(!empty($date_required)){
        $counter_1=0;
        $incremented_date = '';
        for($i=1; $i <= $days; $i++){
            $date = strtotime("+$i day", strtotime($date_required));
            $day_name = date("D", $date);
            $incremented_date = date("Y-m-d", $date);
            if($day_name=='Sat'||$day_name=='Sun'|| in_array($incremented_date ,$holiday_date_array)==true){
                $counter_1+=1;
            }
        }
        if($counter_1 > 0){
            return increase_date($incremented_date, $holiday_date_array, $counter_1);
        }else{
            return $incremented_date;
        }
    }else{
        return 'invalid';
    }
}

echo increase_date($date_required, $holiday_date_array, 15);
?>

//output after adding 15 business working days in 2016-03-01 will be "2016-03-23"

$from = new DateTime($first_date);
$to = new DateTime($second_date);

$to->modify('+1 day');
$interval = $from->diff($to);
$days = $interval->format('%a');

$extra_days = fmod($days, 7);
$workdays = ( ( $days - $extra_days ) / 7 ) * 5;

$first_day = date('N', strtotime($first_date));
$last_day = date('N', strtotime("1 day", strtotime($second_date)));
$extra = 0;
if($first_day > $last_day) {
   if($first_day == 7) {
       $first_day = 6;
   }

   $extra = (6 - $first_day) + ($last_day - 1);
   if($extra < 0) {
       $extra = $extra * -1;
   }
}
if($last_day > $first_day) {
    $extra = $last_day - $first_day;
}
$days = $workdays + $extra

Function get_ business_days_ forward_from_date($num_days, $start_date=", $rtn_ FMT= 'Y-m-d') {

// $start_date will default to today    

if ($start_date=='') { $start_date = date("Y-m-d"); }

$business_day_ct = 0;

$max_days = 10000 + $num_days;  // to avoid any possibility of an infinite loop


// define holidays, this currently only goes to 2012 because, well, you know... ;-)
// if the world is still here after that, you can find more at
// http://www.opm.gov/Operating_Status_Schedules/fedhol/2013.asp
// always add holidays in order, because the iteration will stop when the holiday is > date being tested

$fed_holidays=array(
    "2010-01-01",
    "2010-01-18",
    "2010-02-15",
    "2010-05-31",
    "2010-07-05",
    "2010-09-06",
    "2010-10-11",
    "2010-11-11",
    "2010-11-25",
    "2010-12-24",

    "2010-12-31",
    "2011-01-17",
    "2011-02-21",
    "2011-05-30",
    "2011-07-04",
    "2011-09-05",
    "2011-10-10",
    "2011-11-11",
    "2011-11-24",
    "2011-12-26",

    "2012-01-02",
    "2012-01-16",
    "2012-02-20",
    "2012-05-28",
    "2012-07-04",
    "2012-09-03",
    "2012-10-08",
    "2012-11-12",
    "2012-11-22",
    "2012-12-25",
    );

$curr_date_ymd = date('Y-m-d', strtotime($start_date));    

for ($x=1;$x<$max_days;$x++)
{
    if (intval($num_days)==intval($business_day_ct)) { return(date($rtn_fmt, strtotime($curr_date_ymd))); }  // date found - return

    // get next day to check

    $curr_date_ymd = date('Y-m-d', (strtotime($start_date)+($x * 86400)));   // add 1 day to the current date

    $is_business_day = 1;

    // check if this is a weekend   1 (for Monday) through 7 (for Sunday)

    if ( intval(date("N",strtotime($curr_date_ymd))) > 5) { $is_business_day = 0; }

    //check for holiday
    foreach($fed_holidays as $holiday)
    {
        if (strtotime($holiday)==strtotime($curr_date_ymd))  // holiday found
        {
            $is_business_day = 0;
            break 1;
        }

        if (strtotime($holiday)>strtotime($curr_date_ymd)) { break 1; }  // past date, stop searching (always add holidays in order)


    }

    $business_day_ct = $business_day_ct + $is_business_day;  // increment if this is a business day

} 

// if we get here, you are hosed
return ("ERROR");

}

O add_ business_dias tem um pequeno erro. Tente o seguinte com a função existente e a saída será um sábado.

Data De Início = Sexta-Feira Dias úteis para adicionar = 1 Holidays array = Adicionar data para a segunda-feira seguinte.

Corrigi isso na minha função abaixo.

function add_business_days($startdate, $buisnessdays, $holidays = array(), $dateformat = 'Y-m-d'){
$i= 1;
$dayx= strtotime($startdate);
$buisnessdays= ceil($buisnessdays);

while($i < $buisnessdays)
{
    $day= date('N',$dayx);

    $date= date('Y-m-d',$dayx);
    if($day < 6 && !in_array($date,$holidays))
        $i++;

    $dayx= strtotime($date.' +1 day');
}

## If the calculated day falls on a weekend or is a holiday, then add days to the next business day
$day= date('N',$dayx);
$date= date('Y-m-d',$dayx);

while($day >= 6 || in_array($date,$holidays))
{
    $dayx= strtotime($date.' +1 day');
    $day= date('N',$dayx);
    $date= date('Y-m-d',$dayx);
}

return date($dateformat, $dayx);}

function add_business_days($startdate,$buisnessdays,$holidays,$dateformat){
    $enddate = strtotime($startdate);
    $day = date('N',$enddate);
    while($buisnessdays > 0){ // compatible with 1 businessday if I'll need it
        $enddate = strtotime(date('Y-m-d',$enddate).' +1 day');
        $day = date('N',$enddate);
        if($day < 6 && !in_array(date('Y-m-d',$enddate),$holidays))$buisnessdays--;
    }
    return date($dateformat,$enddate);
}

// as a parameter in in_array function we should use endate formated to 
// compare correctly with the holidays array.

Um aumento da função oferecida por James Pasta acima, para incluir todos os feriados federais ,e para corrigir 4 de julho(foi calculado como 4 de junho acima!), e também incluir o nome de férias como a chave array...

/**
* National American Holidays
* @param string $year
* @return array
*/
Função Pública estática getnacionalamericanholidays ($year) {

//  January 1 - New Year's Day (Observed)
//  Third Monday in January - Birthday of Martin Luther King, Jr.
//  Third Monday in February - Washington’s Birthday / President's Day
//  Last Monday in May - Memorial Day
//  July 4 - Independence Day
//  First Monday in September - Labor Day
//  Second Monday in October - Columbus Day
//  November 11 - Veterans’ Day (Observed)
//  Fourth Thursday in November Thanksgiving Day
//  December 25 - Christmas Day
$bankHolidays = array(
    ['New Years Day'] => $year . "-01-01",
    ['Martin Luther King Jr Birthday'] => "". date("Y-m-d",strtotime("third Monday of January " . $year) ),
    ['Washingtons Birthday'] => "". date("Y-m-d",strtotime("third Monday of February " . $year) ),
    ['Memorial Day'] => "". date("Y-m-d",strtotime("last Monday of May " . $year) ),
    ['Independance Day'] => $year . "-07-04",
    ['Labor Day'] => "". date("Y-m-d",strtotime("first Monday of September " . $year) ),
    ['Columbus Day'] => "". date("Y-m-d",strtotime("second Monday of October " . $year) ),
    ['Veterans Day'] => $year . "-11-11",
    ['Thanksgiving Day'] => "". date("Y-m-d",strtotime("fourth Thursday of November " . $year) ),
    ['Christmas Day'] => $year . "-12-25"
);

return $bankHolidays;

}

Acabei de escrever uma API que pode ser usada para manipular dias úteis( nenhuma destas soluções funcionou muito bem para a minha situação: -); ligando-a aqui no caso de mais alguém achar útil.

Classe PHP para calcular OS Dias Úteis

<?php
function count_business_days($date, $days, $holidays) {
    $date = strtotime($date);

    for ($i = 1; $i <= intval($days); $i++) { //Loops each day count

        //First, find the next available weekday because this might be a weekend/holiday
        while (date('N', $date) >= 6 || in_array(date('Y-m-d', $date), $holidays)){
            $date = strtotime(date('Y-m-d',$date).' +1 day');
        }

        //Now that we know we have a business day, add 1 day to it
        $date = strtotime(date('Y-m-d',$date).' +1 day');

        //If this day that was previously added falls on a weekend/holiday, then find the next business day
        while (date('N', $date) >= 6 || in_array(date('Y-m-d', $date), $holidays)){
            $date = strtotime(date('Y-m-d',$date).' +1 day');
        }
    }
    return date('Y-m-d', $date);
}

//Also add in the code from Tony and James Pasta to handle holidays...

function getNationalAmericanHolidays($year) {
$bankHolidays = array(
    'New Years Day' => $year . "-01-01",
    'Martin Luther King Jr Birthday' => "". date("Y-m-d",strtotime("third Monday of January " . $year) ),
    'Washingtons Birthday' => "". date("Y-m-d",strtotime("third Monday of February " . $year) ),
    'Memorial Day' => "". date("Y-m-d",strtotime("last Monday of May " . $year) ),
    'Independance Day' => $year . "-07-04",
    'Labor Day' => "". date("Y-m-d",strtotime("first Monday of September " . $year) ),
    'Columbus Day' => "". date("Y-m-d",strtotime("second Monday of October " . $year) ),
    'Veterans Day' => $year . "-11-11",
    'Thanksgiving Day' => "". date("Y-m-d",strtotime("fourth Thursday of November " . $year) ),
    'Christmas Day' => $year . "-12-25"
);
return $bankHolidays;

}

//Now to call it... since we're working with business days, we should
//also be working with business hours so check if it's after 5 PM
//and go to the next day if necessary.

//Go to next day if after 5 pm (5 pm = 17)
if (date(G) >= 17) {
    $start_date = date("Y-m-d", strtotime("+ 1 day")); //Tomorrow
} else {
    $start_date = date("Y-m-d"); //Today
}

//Get the holidays for the current year and also for the next year
$this_year = getNationalAmericanHolidays(date('Y'));
$next_year = getNationalAmericanHolidays(date('Y', strtotime("+12 months")));
$holidays = array_merge($this_year, $next_year);

//The number of days to count
$days_count = 10;

echo count_business_days($start_date, $days_count, $holidays);

?>

function onlyWorkDays( $d ) {
    $holidays = array('2013-12-25','2013-12-31','2014-01-01','2014-01-20','2014-02-17','2014-05-26','2014-07-04','2014-09-01','2014-10-13','2014-11-11','2014-11-27','2014-12-25','2014-12-31');
    while (in_array($d->format("Y-m-d"), $holidays)) { // HOLIDAYS
        $d->sub(new DateInterval("P1D"));
    }
    if ($d->format("w") == 6) { // SATURDAY
        $d->sub(new DateInterval("P1D"));
    }
    if ($d->format("w") == 0) { // SUNDAY
        $d->sub(new DateInterval("P2D"));
    }
    return $d;
}

Basta enviar a data proposta new para esta função.

Acabei de criar esta função, que parece funcionar muito bem:

function getBusinessDays($date1, $date2){

    if(!is_numeric($date1)){
        $date1 = strtotime($date1);
    }

    if(!is_numeric($date2)){
        $date2 = strtotime($date2);
    }

    if($date2 < $date1){
        $temp_date = $date1;
        $date1 = $date2;
        $date2 = $temp_date;
        unset($temp_date);
    }

    $diff = $date2 - $date1;

    $days_diff = intval($diff / (3600 * 24));
    $current_day_of_week = intval(date("N", $date1));
    $business_days = 0;

    for($i = 1; $i <= $days_diff; $i++){
        if(!in_array($current_day_of_week, array("Sunday" => 1, "Saturday" => 7))){
            $business_days++;
        }

        $current_day_of_week++;
        if($current_day_of_week > 7){
            $current_day_of_week = 1;
        }
    }

    return $business_days;
}

echo "Business days: " . getBusinessDays("8/15/2014", "8/8/2014");

As PHPClasses têm uma boa classe para este chamado PHP dias de trabalho. Podes verificar esta aula.

Calcular os dias úteis entre duas datas, Incluindo férias e semana de trabalho personalizado

A resposta não é tão trivial - assim a minha sugestão seria usar uma classe onde você pode configurar mais do que depender de uma função simplista (ou assumindo um local e cultura fixos). Para obter a data após um certo número de dias de trabalho você vai:

1. é necessário indicar os dias úteis em que irá trabalhar (por omissão às segundas-feiras) - a classe permite-lhe activar ou desactivar todos os dias da semana individualmente.
2. preciso de saber que tem de considerar os feriados públicos (país e estado) exactos
   • por exemplo https://github.com/khatfield/php-HolidayLibrary/blob/master/Holidays.class.php
   • ou código rígido os dados: por exemplo de http://www.feiertagskalender.ch/?hl=en
   • ou pagar por dados-API http://www.timeanddate.com/services/api/holiday-api.html

Abordagem Funcional

/**
 * @param days, int
 * @param $format, string: dateformat (if format defined OTHERWISE int: timestamp) 
 * @param start, int: timestamp (mktime) default: time() //now
 * @param $wk, bit[]: flags for each workday (0=SUN, 6=SAT) 1=workday, 0=day off
 * @param $holiday, string[]: list of dates, YYYY-MM-DD, MM-DD 
 */
function working_days($days, $format='', $start=null, $week=[0,1,1,1,1,1,0], $holiday=[])
{
    if(is_null($start)) $start = time();
    if($days <= 0) return $start;
    if(count($week) != 7) trigger_error('workweek must contain bit-flags for 7 days');
    if(array_sum($week) == 0) trigger_error('workweek must contain at least one workday');
    $wd = date('w', $start);//0=sun, 6=sat
    $time = $start;
    while($days)
    {
        if(
        $week[$wd]
        && !in_array(date('Y-m-d', $time), $holiday)
        && !in_array(date('m-d', $time), $holiday)
        ) --$days; //decrement on workdays
        $wd = date('w', $time += 86400); //add one day in seconds
    }
    $time -= 86400;//include today
    return $format ? date($format, $time): $time;
}

//simple usage
$ten_days = working_days(10, 'D F d Y');
echo '<br>ten workingdays (MON-FRI) disregarding holidays: ',$ten_days;

//work on saturdays and add new years day as holiday
$ten_days = working_days(10, 'D F d Y', null, [0,1,1,1,1,1,1], ['01-01']);
echo '<br>ten workingdays (MON-SAT) disregarding holidays: ',$ten_days;

Esta é outra solução, é quase 25% mais rápido do que verificar os feriados com o in_array:

/**
 * Function to calculate the working days between two days, considering holidays.
 * @param string $startDate -- Start date of the range (included), formatted as Y-m-d.
 * @param string $endDate -- End date of the range (included), formatted as Y-m-d.
 * @param array(string) $holidayDates -- OPTIONAL. Array of holidays dates, formatted as Y-m-d. (e.g. array("2016-08-15", "2016-12-25"))
 * @return int -- Number of working days.
 */
function getWorkingDays($startDate, $endDate, $holidayDates=array()){
    $dateRange = new DatePeriod(new DateTime($startDate), new DateInterval('P1D'), (new DateTime($endDate))->modify("+1day"));
    foreach ($dateRange as $dr) { if($dr->format("N")<6){$workingDays[]=$dr->format("Y-m-d");} }
    return count(array_diff($workingDays, $holidayDates));
}