Question

Why does PHP return INF (infinity) for the following piece of code:

<?php
$n = 1234;
$m = 0;

while ($n > 0)
{
    $m = ($m * 10) + ($n % 10);
    $n = $n / 10;
}

var_dump($m);
?>

The expected result was 4321, but PHP returned INF, float type:

float INF

I wrote the same code in Python and C# and got the expected output – 4321

Python

n = 1234
m = 0

while (n > 0):
    m = (m * 10) + (n % 10)
    n = n / 10

print m

C#

static void Main(string[] args)
{
    int n = 1234;
    int m = 0;

    while (n > 0)
    {
        m = (m * 10) + (n % 10);
        n = n / 10;
    }

    Console.WriteLine(m);
    Console.ReadLine();
}

Answer 1

In php $n / 10 will return a float number, not integer.

So $n > 0 will always be true.

Change while($n > 0)

to while($n > 1) or while((int)$n > 0), then you will get the right result.