Question

I know how to convert binary to decimal. I know at least 2 methods: table and power 😉

I want to convert binary to decimal and print this decimal. Moreover, I’m not interested in this `decimal’; I want just to print it.

But, as I wrote above, I know only 2 methods to convert binary to decimal and both of them required addition. So, I’m computing some value for 1 or 0 in binary and add it to the remembered value. This is a thin place. I have a really-really big number (1 and 64 zeros). While converting I need to place some intermediate result in some ‘variable’. In C, I have an `int’ type, which is 4 bytes only and not more than 10^11.

So, I don’t have enough memory to store intermedite result while converting from binary to decimal. As I wrote above, I’m not interested in THAT decimal, I just want to print the result. But, I don’t see any other ways to solve it ;-( Is there any solution to “just print” from binary?

Or, maybe, I should use something like BCD (Binary Coded Decimal) for intermediate representation? I really don’t want to use this, ’cause it is not so cross-platform (Intel’s processors have a built-in feature, but for other I’ll need to write own implementation).

I would glad to hear your thoughts. Thanks for patience.

Language: C.

Answer 1

Biggest standard integral data type is unsigned long long int – on my system (32-bit Linux on x86) it has range 0 – 1.8*10^20 which is not enough for you, so you need to create your own type (struct or array) and write basic math (basically you just need an addition) for that type.

If I were you (and memory is not an issue), I’d use an array – one byte per decimal digit rather then BCD. BCD is more compact as it stores 2 decimal digits per byte but you need to put much more effort working with high and low nibbles separately.

And to print you just add '0' (character, not digit) to every byte of your array and you get a printable string.