Overflow with integer

Question

I want to convert the number from decimal to hexadecimal number. The problems is the number is too big that cannot store in int datatype.For example,

int a = pow(10,17);

However, if I try to use double, I will face the problem of modulo operator because it does not support floating point datatype.

What should I do to convert it and store it? (Project Euler Problem Number 162).

Why not use `long`? See http://stackoverflow.com/a/900245/836214 — Krease, Jan 07 '14 at 08:31
Even long int cannot store such of very big data, pow(10,17) — MakaraPr, Jan 07 '14 at 08:31
If a 64-bit datatype such as `unsigned long long` can't handle it, you have to use a library such as [gmplib](https://gmplib.org/). — Some programmer dude, Jan 07 '14 at 08:32
If it's only because you have doubles, can't you use `fmod`? — Roger Rowland, Jan 07 '14 at 08:34
Regarding what you try to do (convert decimal to hexadecimal), can't you just print the numbers as hexadecimal? And if you have a normal `int` variable you try to convert (and you have to do it yourself, and not use e.g. `snprintf`) then it's just a couple of simple bitwise operations needed (masking and shifting) together with a comparison. — Some programmer dude, Jan 07 '14 at 08:38
@MakaraPr _'Even long int cannot store such of very big data, pow(10,17)'_ Note that 2^64 is way bigger than 10^17! If you work with `unsigned long long` your results should fit in well there. — πάντα ῥεῖ, Jan 07 '14 at 08:46

score 0 · Accepted Answer · edited May 23 '17 at 10:25

0

use can use long for that

You can convert int to long simply by

long variable=(long)a;

If that don't meet your requiremnet

You can use long long long long in C/C++

Conversion:

long long variable = (long long) a;

edited May 23 '17 at 10:25

Community

answered Jan 07 '14 at 08:37

Sajad Karuthedath

1

On some platforms (e.g. Windows) `long` is the same size as `int`. – Some programmer dude Jan 07 '14 at 08:38
then he can use long long – Sajad Karuthedath Jan 07 '14 at 08:44
He can use int64_t if he uses C++11. http://en.cppreference.com/w/cpp/types/integer – olevegard Jan 07 '14 at 08:45
@olevegard: please refer this link http://stackoverflow.com/questions/12468281/should-i-use-long-long-or-int64-t-for-portable-code – Sajad Karuthedath Jan 07 '14 at 08:49
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@SajadLfc `long long` isn't part of the standard though( as far as I can tell ) But yeah, but since `long long` is at least 64 bytes it should be the best choice if `C++11` is not an option – olevegard Jan 07 '14 at 09:02

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