Create string in one character at a time with loop

Question

I am trying to create a string of every hour in the week starting at 0. The string would be 167 characters long and consist of 0/1 for every character representing true/false for that hour.

I know you can edit strings as so :

$foo = "123456789";
echo $foo[0]; // outs 1
echo $foo[1]; //outs 2

$foo[0] = 1;
$foo[1] = 1;

echo $foo[0]; // outs 1
echo $foo[1]; // outs 1

So I assumed I could set a blank string and use the same method to 'build' it. So I am running a loop from 0-167 and while doing so checking if the 'hour' is in the $hours array. If it is I set it to 1 in my string... if not it is set to 0. Problems :

1. This does not work by setting $inputHours = '' and it just creates an array instead of the string I want.

2. Is there a more optimized manner to check if an hour is set other than using in_array 167 times?

//array of selected hours
$hours = array(1, 25, 34, 76, 43)

//create selected hours string from selection
$inputHours = '';

for ($x = 0; $x < 168; $x++) {
    $inputHours[$x] = in_array($x, $hours) ? 1 : 0; 
} 

Expected output would be $inputHours = '0011010101...' depending if set for a total lenth of 167 characters.

Answer 1

You can concatenate characters in one string with .= operator and check condition using ternary operator ([expression] ? [true] : [false]) with in_array() function:

for($x = 0; $x < 168; $x++)
    $inputHours .= in_array($x, $hours) ? 1 : 0;

Example