GCC option for printing large number (large double)

Question

I have an issue in printing a large number in a c program. Please find below the code snippet :

int main()
{
 double temp = 0.0;
 temp = pow(2, 2000);
 printf("The value of temp is %lfn", temp);
 return 0;
}

I compiled and ran as below:

$ gcc test.c -o test
$ ./test
The value of temp is inf

But for the same expression, I am able to get the value from python,

$ python
>>> pow(2,2000)
1148130..........................49029376L
>>>

Can any body help me with that option?

Answer 1

There is no GCC option that will help you here. Python and C are two different languages and they represent numbers in different ways. To do this kind of thing in C you will need to use some sort of bignum library, such as libmpfr.

Answer 2

I would suggest you have a look at the Gnu MP library, which deals with big integers, floats and gives you lots of things that you can normally find in languages like Python, Go or Java.

An example would be:

 mpz_t a;
 mpz_init(a);
 mpz_set_str(a, "10000000000000000000000000000", 10);
 gmp_printf("%Zd", a);
 mpz_clear(a);

which will print this number back to you, and %Zx will print the Hex version of it.