How to use 12 digit number in C?

Question

I am dealing with a math example. I need to use 12 digit number for my code. So which datatype should i use, to use the number in my functions?

Krystalkrystalle

Answer 1

64-bit integers (long, int64_t, unsigned long, uint64_t) should do the trick, or if you need decimals, double or long double.

Deyo

If you need decimals you're out of luck in pure C; double and long double are floating point types, not decimal ones. – Pitzer

No. I did mention 64-bit integers too, which can hold well over 12 digits even when signed! – Deyo

what should i use for example while printing them? "%ld" was for long as far i remembered? – Krystalkrystalle

Yes. %ld is the correct format specifier. Use %lu if it's an unsigned long, however. – Deyo

Check out <inttypes.h>. It has printf() / scanf() format specifiers for the intX_t types (among others). – Intolerant

You should not recommend long as a 64-bit type. It's 32-bit on most systems and the C standard only requires it to be at least 32-bit. – Jarredjarrell

Answer 2

If you have a 64-bit integer type, I'd go with that, since it gives you the (18 full digits) range:

−9,223,372,036,854,775,808 to
+9,223,372,036,854,775,807

For other tasks (even bigger integers or massive floating point values), I use GMP, the GNU multi-precision library. It's performance is impressive.

Febricity

Answer 3

you can also use "unsigned long long" with format specifier "llu". It works fine for 12 digit number in C.

unsigned long long i=600851475143;
printf("%llu",i);

Milkwort