<?php

function addOneToBinary($binaryStr) {

// Initialize the result string and carry

$result = '';

$carry = 1; // We are adding one, so the initial carry is 1

// Loop through the binary string from the end to the beginning

for ($i = strlen($binaryStr) - 1; $i >= 0; $i--) {

$char = $binaryStr[$i];

if ($char == '0') {

if ($carry) {

$result = '1' . $result;

$carry = 0;

} else {

$result = '0' . $result;

}

} else { // $char == '1'

if ($carry) {

$result = '0' . $result;

$carry = 1; // Still need to carry over

} else {

$result = '1' . $result;

}

}

}

// If there's still a carry left after the loop, prepend '1' to the result

if ($carry) {

$result = '1' . $result;

}

return $result;

}

// Input from the user

echo "Enter a binary string: ";

$handle = fopen("php://stdin", "r");

$n = trim(fgets($handle));

fclose($handle);

$result = addOneToBinary($n);

echo "The binary representation of $n + 1 is $result\n";