public static int mpfr_strtofr(
	mpfr_t rop,
	char_ptr nptr,
	ref char_ptr endptr,
	int base,
	mpfr_rnd_t rnd
)

Public Shared Function mpfr_strtofr ( 
	rop As mpfr_t,
	nptr As char_ptr,
	ByRef endptr As char_ptr,
	base As Integer,
	rnd As mpfr_rnd_t
) As Integer

public:
static int mpfr_strtofr(
	mpfr_t^ rop, 
	char_ptr nptr, 
	char_ptr% endptr, 
	int base, 
	mpfr_rnd_t rnd
)

static member mpfr_strtofr : 
        rop : mpfr_t * 
        nptr : char_ptr * 
        endptr : char_ptr byref * 
        base : int * 
        rnd : mpfr_rnd_t -> int 

Parameters

rop

Type: Math.Mpfr.Nativempfr_t
The result floating-point number.

nptr

Type: Math.Gmp.Nativechar_ptr
String containing a floating-point number.

endptr

Type: Math.Gmp.Nativechar_ptr
On return, points the first character after floating-point number in nptr.

base

Type: SystemInt32
The base.

rnd

Type: Math.Mpfr.Nativempfr_rnd_t
The rounding direction.

Return Value

The base must be either 0 (to detect the base, as described below) or a number from 2 to 62 (otherwise the behavior is undefined). If nptr starts with valid data, the result is stored in rop and endptr points to the character just after the valid data (if endptr is not a null pointer); otherwise rop is set to zero (for consistency with strtod) and the value of nptr is stored in the location referenced by endptr (if endptr is not a null pointer). The usual ternary value is returned.

Parsing follows the standard C strtod function with some extensions. After optional leading whitespace, one has a subject sequence consisting of an optional sign (+ or -), and either numeric data or special data. The subject sequence is defined as the longest initial subsequence of the input string, starting with the first non-whitespace character, that is of the expected form.

The form of numeric data is a non-empty sequence of significand digits with an optional decimal point, and an optional exponent consisting of an exponent prefix followed by an optional sign and a non-empty sequence of decimal digits. A significand digit is either a decimal digit or a Latin letter (62 possible characters), with A = 10, B = 11, …, Z = 35; case is ignored in bases less or equal to 36, in bases larger than 36, a = 36, b = 37, …, z = 61. The value of a significand digit must be strictly less than the base. The decimal point can be either the one defined by the current locale or the period (the first one is accepted for consistency with the C standard and the practice, the second one is accepted to allow the programmer to provide MPFR numbers from strings in a way that does not depend on the current locale). The exponent prefix can be e or E for bases up to 10, or @ in any base; it indicates a multiplication by a power of the base. In bases 2 and 16, the exponent prefix can also be p or P, in which case the exponent, called binary exponent, indicates a multiplication by a power of 2 instead of the base (there is a difference only for base 16); in base 16 for example 1p2 represents 4 whereas 1@2 represents 256. The value of an exponent is always written in base 10.

If the argument base is 0, then the base is automatically detected as follows. If the significand starts with 0b or 0B, base 2 is assumed. If the significand starts with 0x or 0X, base 16 is assumed. Otherwise base 10 is assumed.

Note: The exponent (if present) must contain at least a digit. Otherwise the possible exponent prefix and sign are not part of the number (which ends with the significand). Similarly, if 0b, 0B, 0x or 0X is not followed by a binary/hexadecimal digit, then the subject sequence stops at the character 0, thus 0 is read.

Special data (for infinities and NaN) can be @inf@ or @nan@(n-char-sequence-opt), and if base ≤ 16, it can also be infinity, inf, nan or nan(n-char-sequence-opt), all case insensitive. A n-char-sequence-opt is a possibly empty string containing only digits, Latin letters and the underscore (0, 1, 2, …, 9, a, b, …, z, A, B, …, Z, _). Note: one has an optional sign for all data, even NaN. For example, -@nAn@(This_Is_Not_17) is a valid representation for NaN in base 17.

Reference