'PHP, how to convert Int value to Week days

For saving the days of week in a database, I've the existing code :

if (isset($_POST['day7'])){$dayOfWeek = 1;} else { $dayOfWeek = ''; }
if (isset($_POST['day1'])){$dayOfWeek = $dayOfWeek + 2;}
if (isset($_POST['day2'])){$dayOfWeek = $dayOfWeek + 4;}
if (isset($_POST['day3'])){$dayOfWeek = $dayOfWeek + 8;}
if (isset($_POST['day4'])){$dayOfWeek = $dayOfWeek + 16;}
if (isset($_POST['day5'])){$dayOfWeek = $dayOfWeek + 32;}
if (isset($_POST['day6'])){$dayOfWeek = $dayOfWeek + 64;}

For exemple : Monday, Friday, Saturday is : int(98) (2+32+64) bin value for that = 1100010

Other exemple : Sunday, Monday = int(3) (2+1) Bin value = 11

My question is : How to do the reverse in order to get the days of week in : exemple : String(Mon, Fri, Sat) from the int value ?

I can do it with a binary value like 1100010, but I don't understand how to do it when the binary is less than 7 "characters", like 11

<?php
function binToWeekdays($binvalue) {

    $array_week = array();
    $array_week = str_split($binvalue);
    $array_week = array_reverse($array_week);

    $weekdays = '';

    if ($array_week[1] == 1) {
        $weekdays .= 'Mon, ';
    }
    if ($array_week[2] == 1) {
        $weekdays .= 'Tue, ';
    }
    if ($array_week[3] == 1) {
        $weekdays .= 'Wed, ';
    }
    if ($array_week[4] == 1) {
        $weekdays .= 'Thu, ';
    }
    if ($array_week[5] == 1) {
        $weekdays .= 'Fri, ';
    }
    if ($array_week[6] == 1) {
        $weekdays .= 'Sat, ';
    }
    if ($array_week[0] == 1) {
        $weekdays .= 'Sun';
    }

    return $weekdays;

}

echo binToWeekdays('1100010');

?>

Returns : Mon, Fri, Sat,

Thanks for your help

phpintegerbindays


Solution 1:[1]

other idea (instead of padding the string with zeros):

convert the binary value to an integer and use the binary &-operator for checking if a day is selected:

function binToWeekdays($binvalue) {
  $decvalue = bindec($binvalue);
  $weekdays = array();
  if($decvalue & 1 << 1){
    $weekdays[] = 'Mon';
  }
  if($decvalue & 1 << 2){
    $weekdays[] = 'Tue';
  }
  if($decvalue & 1 << 3){
    $weekdays[] = 'Wed';
  }
  if($decvalue & 1 << 4){
    $weekdays[] = 'Thu';
  }
  if($decvalue & 1 << 5){
    $weekdays[] = 'Fri';
  }
  if($decvalue & 1 << 6){
    $weekdays[] = 'Sat';
  }
  if($decvalue & 1 << 0){
    $weekdays[] = 'Sun';
  }
  return implode(', ', $weekdays);
}

echo binToWeekdays('1100010') . "<br />\n"; // => Mon, Fri, Sat
echo binToWeekdays('11') . "<br />\n"; // =>  Mon, Sun

In addition I have used an array and imploded this before returning to prevent a trailing comma if there is no sunday selected.

Solution 2:[2]

Picking up the accepted solution from Matthias Radde (which I liked because of the use of binary operators), but now able to define the map of a weekdays bit position...

function binToWeekdays($binvalue, $map) {
    $decvalue = bindec($binvalue);
    $weekdays = [];
    
    foreach($map as $day => $exp){
        if (($decvalue & (1 << $exp)) != 0) {
            $weekdays[] = $day;
        }
    }
    return implode(', ', $weekdays);
}

// with sunday = 0
$map = [
    'Sun' => 0,'Mon' => 1,'Tue' => 2,
    'Wed' => 3,'Thu' => 4,'Fri' => 5,'Sat' => 6,
];  

echo binToWeekdays('1100010', $map) . "<br />\n"; // => Mon, Fri, Sat
echo binToWeekdays('11', $map) . "<br />\n"; // =>  Mon, Sun

// with monday = 0
$map = [
    'Mon' => 0,'Tue' => 1,'Wed' => 2,
    'Thu' => 3,'Fri' => 4,'Sat' => 5,'Sun' => 6,
];  

echo binToWeekdays('1100010', $map) . "<br />\n"; // => Tue, Sat, Sun
echo binToWeekdays('11', $map) . "<br />\n"; // =>  Mon, Tue

Solution 3:[3]

How about "str_pad" ? If the binary is less than 7 "characters",

str_pad(1,7,"0",STR_PAD_LEFT)

Solution 4:[4]

You can simply pad the string with zeros:

function binToWeekdays($binvalue) {

    $binvalue = str_pad($binvalue, 7, "0", STR_PAD_LEFT);
    $array_week = array_reverse(str_split($binvalue));

    $weekdays = '';

    if ($array_week[1] == 1) {
        $weekdays .= 'Mon, ';
    }
    if ($array_week[2] == 1) {
        $weekdays .= 'Tue, ';
    }
    if ($array_week[3] == 1) {
        $weekdays .= 'Wed, ';
    }
    if ($array_week[4] == 1) {
        $weekdays .= 'Thu, ';
    }
    if ($array_week[5] == 1) {
        $weekdays .= 'Fri, ';
    }
    if ($array_week[6] == 1) {
        $weekdays .= 'Sat, ';
    }
    if ($array_week[0] == 1) {
        $weekdays .= 'Sun';
    }

    return $weekdays;

}

echo binToWeekdays('11');

This outputs:

Mon, Sun

Live demo: https://3v4l.org/pSl8I

Documentation: https://www.php.net/manual/en/function.str-pad.php

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1
Solution 2 Honk der Hase
Solution 3 Li Yong
Solution 4

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