How to do Modulo (double and Big Numbers)

Schehaider_Aymen

Hi all. I was wondering why a modf ( modulo for float doesn't do its job : I explain) i have a Big Number X = 1051450100212345678903111694, so as i can't handle it into regular int, _int64, long int i used the double var type. but the % (modulo) for float is located in cmath by the modf function so when i want to calculate

double x = 1051450100212345678903111694;
double BigX = 100 * x;
double y = 97;

double z = modf(BigX, & y);

i always have 0 in z

ok why not writing some code doing the regular job.

while (BigX >97)
BigX = BigX - (BigX/97);

ok But in the second code the result will 96.0111 (sth like that) or when i do it with the Calculator of windows it shows me 92 which differs so how could i do such modulo for big numbers ??? Thx U

"The Ultimate Limit Is Only Your Imagination."

Lost User

Blood_HaZaRd wrote:

i always have 0 in z

That's because there is no fractional part in your value; both x and BigX in your sample are whole numbers. See the description of modf()[^].

It's time for a new signature.

CPallini

Blood_HaZaRd wrote:

i have a Big Number X = 1051450100212345678903111694, so as i can't handle it into regular int, _int64, long int i used the double var type.

A double cannot handle it with the necessary accuracy, the following code

double x = 1051450100212345678903111694.;
printf("%20f",x);

outputs

1051450100212345700000000000.000000

:)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
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[My articles]

Peter_in_2780

You will need to get (or write) a big-integer library. Google will find lots, such as http://mattmccutchen.net/bigint/[^] Disclaimer: I have nothing to do with Matt, except that I downloaded his library.

Software rusts. Simon Stephenson, ca 1994.

Schehaider_Aymen

Thx It seems That i missunderstood The modf . ^^ thx ;P

"The Ultimate Limit Is Only Your Imagination."

Schehaider_Aymen

Great Library but could i Use some Commons var, i don't like going for others library :p

"The Ultimate Limit Is Only Your Imagination."

Schehaider_Aymen

i 've got errors

error C2258: illegal pure syntax, must be '= 0'
error C2252: 'less' : pure specifier can only be specified for functions
error C2258: illegal pure syntax, must be '= 0'
error C2252: 'equal' : pure specifier can only be specified for functions
error C2258: illegal pure syntax, must be '= 0'
error C2252: 'greater' : pure specifier can only be specified for functions

Just here

class BigInteger {

public:
typedef BigUnsigned::Blk Blk;
typedef BigUnsigned::Index Index;
typedef BigUnsigned::CmpRes CmpRes;
static const CmpRes
less = BigUnsigned::less ,
equal = BigUnsigned::equal ,
greater = BigUnsigned::greater;
// Enumeration for the sign of a BigInteger.
enum Sign { negative = -1, zero = 0, positive = 1 };

protected:
Sign sign;
BigUnsigned mag;

:omg:

"The Ultimate Limit Is Only Your Imagination."

Niklas L

Looks like you use an old compiler not supporting initialization of static const vars in class declaration. Initialize them in cpp-file instead if BigInteger is your own class.

home

Schehaider_Aymen

lool ok how Unlucky i am

"The Ultimate Limit Is Only Your Imagination."

Aescleal

I'm a bit confused: 0xE97804B9A34AB4E fits in an __int64 with a nibble to spare. I know it depends what your compiler is and __int64 isn't a standard type but if you've got it and it doesn't need to be portable then why not use it? Ash PS: I'm normally against using non-portable code but at least someone trying to compile your code for a platform with a 64 bit int would at least be warned something was up. PPS: And if you need to store it in 32 bit values you can take advantage of some properties of ints that makes it relatively easy to calculate the modulus.