A Question

[_Exile]

I have the following code which converts to from base-10 to base-2 numbers:

static char binary[50];
char* ptr = &binary[sizeof(binary)-1];

*ptr = '\0';
while(n != 0)
{
	*--ptr = "0123456789abcdef"[n % 2];
	n /= 2;
}

I understand everything except

 "0123456789abcdef"[n % 2];

I've got this line from someone's code

As far as i understand this is supposed to decrease the pointer and dereference it to fill the next (or previous since we work in binary) element but what does the "0123456789absded" do?

I've tried to replace it with other values but apparently it have to be hexadecimal.

Thanks

[Lindley]

The only relevant part of that is "01", since it's impossible for n%2 to be anything other than 0 or 1. It's simply selecting the proper character to add to the string.

As for why the other characters are there? Presumably, to make it easier to change the function so that it converts to a different base.

[_Exile]

Thank you Lindley,

I won't be using it since it's not safe, But i still curious to know what does these characters do in this case?

Regards

[Lindley]

It's just a literal string. You can think of it as an array containing those characters if you want.

And I retract my comment about safety----50 characters should be enough to handle the binary representation of any 32-bit int, obviously. 64-bit ints would be an issue.

The simplest way to do this conversion, though, is to use std::bitset<N>::to_string().

[_Exile]

Thanks Lindley,
I would use the method you've provided next time I was just training myself to work with those types.

Regards