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# (gmp.info.gz) Converting Integers

Info Catalog (gmp.info.gz) Simultaneous Integer Init & Assign (gmp.info.gz) Integer Functions (gmp.info.gz) Integer Arithmetic
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Conversion Functions
====================

This section describes functions for converting GMP integers to
standard C types.  Functions for converting _to_ GMP integers are
described in  Assigning Integers and  I/O of Integers.

- Function: unsigned long int mpz_get_ui (mpz_t OP)
Return the value of OP as an `unsigned long'.

If OP is too big to fit an `unsigned long' then just the least
significant bits that do fit are returned.  The sign of OP is
ignored, only the absolute value is used.

- Function: signed long int mpz_get_si (mpz_t OP)
If OP fits into a `signed long int' return the value of OP.
Otherwise return the least significant part of OP, with the same
sign as OP.

If OP is too big to fit in a `signed long int', the returned
result is probably not very useful.  To find out if the value will
fit, use the function `mpz_fits_slong_p'.

- Function: double mpz_get_d (mpz_t OP)
Convert OP to a `double', truncating if necessary (ie. rounding
towards zero).

If the exponent from the conversion is too big, the result is
system dependent.  An infinity is returned where available.  A
hardware overflow trap may or may not occur.

- Function: double mpz_get_d_2exp (signed long int *EXP, mpz_t OP)
Convert OP to a `double', truncating if necessary (ie. rounding
towards zero), and returning the exponent separately.

The return value is in the range 0.5<=abs(D)<1 and the exponent is
stored to `*EXP'.  D * 2^EXP is the (truncated) OP value.  If OP
is zero, the return is 0.0 and 0 is stored to `*EXP'.

This is similar to the standard C `frexp' function (
Normalization Functions (libc)Normalization Functions.).

- Function: char * mpz_get_str (char *STR, int BASE, mpz_t OP)
Convert OP to a string of digits in base BASE.  The base may vary
from 2 to 36.

If STR is `NULL', the result string is allocated using the current
allocation function ( Custom Allocation).  The block will be
`strlen(str)+1' bytes, that being exactly enough for the string and
null-terminator.

If STR is not `NULL', it should point to a block of storage large
enough for the result, that being `mpz_sizeinbase (OP, BASE) + 2'.
The two extra bytes are for a possible minus sign, and the
null-terminator.

A pointer to the result string is returned, being either the
allocated block, or the given STR.

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