Standard C Library Functions stringtodecimal(3C)
NAME
stringtodecimal, filetodecimal, functodecimal - parse
characters into decimal record
SYNOPSIS
#include
void stringtodecimal(char **pc, int nmax,
int fortranconventions, decimalrecord *pd,
enum decimalstringform *pform, char **pechar);
void functodecimal(char **pc, int nmax,
int fortranconventions, decimalrecord *pd,
enum decimalstringform *pform, char **pechar,
int (*pget)(void), int *pnread, int (*punget)(int c));
#include
void filetodecimal(char **pc, int nmax,
int fortranconventions, decimalrecord *pd,
enum decimalstringform *pform, char **pechar,
FILE *pf, int *pnread);
DESCRIPTION
These functions attempt to parse a numeric token from at
most nmax characters read from a string **pc, a file *pf, or
function (*pget). They set the decimal record *pd to reflect
the value of the numeric token recognized and set *pform and
*pechar to indicate its form.
The accepted forms for the numeric token consist of an ini-
tial, possibly empty, sequence of white-space characters, as
defined by isspace(3C), followed by a subject sequence
representing a numeric value, infinity, or NaN. The subject
sequence consists of an optional plus or minus sign followed
by one of the following:
o a non-empty sequence of decimal digits optionally
containing a decimal point character, then an
optional exponent part
o one of INF or INFINITY, ignoring case
o one of NAN or NAN(string), ignoring case in the NAN
part; string can be any sequence of characters not
containing ')' (right parenthesis) or '\0' (null).
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Standard C Library Functions stringtodecimal(3C)
The fortranconventions argument provides additional control
over the set of accepted forms. It must be one of the fol-
lowing values:
0 no Fortran conventions
1 Fortran list-directed input conventions
2 Fortran formatted input conventions, blanks are ignored
3 Fortran formatted input conventions, blanks are inter-
preted as zeroes
When fortranconventions is zero, the decimal point charac-
ter is the current locale's decimal point character, and the
exponent part consists of the letter E or e followed by an
optional sign and a non-empty string of decimal digits.
When fortranconventions is non-zero, the decimal point
character is "." (period), and the exponent part consists of
either a sign or one of the letters E, e, D, d, Q, or q fol-
lowed by an optional sign, then a non-empty string of
decimal digits.
When fortranconventions is 2 or 3, blanks can appear in the
digit strings for the integer, fraction, and exponent parts,
between the exponent delimiter and optional exponent sign,
and after an INF, INFINITY, NAN, or NAN(string). When
fortranconventions is 2, all blanks are ignored. When
fortranconventions is 3, blanks in digit strings are inter-
preted as zeros and other blanks are ignored.
The following table summarizes the accepted forms and shows
the corresponding values to which *pform and pd->fpclass are
set. Here digits represents any string of decimal digits,
"." (period) stands for the decimal point character, and
exponent represents the exponent part as defined above.
Numbers in brackets refer to the notes following the table.
form *pform pd->fpclass
all white space [1] whitespaceform fpzero
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Standard C Library Functions stringtodecimal(3C)
digits fixedintform fpnormal [2]
digits. fixedintdotform fpnormal [2]
.digits fixeddotfracform fpnormal [2]
digits.digits fixedintdotfracform fpnormal [2]
digits exponent floatingintform fpnormal [2]
digits. exponent floatingintdotform fpnormal [2]
.digits exponent floatingdotfracform fpnormal [2]
digits.digits exponent floatingintdotfracform fpnormal [2]
INF infform fpinfinity
INFINITY infinityform fpinfinity
NAN nanform fpquiet
NAN(string) nanstringform fpquiet
none of the above invalidform fpsignaling
Notes:
1. The whitespaceform is accepted only when
fortranconventions is 2 or 3 and is interpreted as
zero.
2. For all numeric forms, pd->fpclass is set to
fpnormal if any non-zero digits appear in the
integer or fraction parts, and otherwise pd-
>fpclass is set to fpzero.
If the accepted token has one of the numeric forms and
represents a non-zero number x, its significant digits are
stored in pd->ds. Leading and trailing zeroes and the radix
point are omitted. pd->sign and pd->exponent are set so
that if m is the integer represented by pd->ds,
-1**(pd->sign) * m * 10**(pd->exponent)
approximates x to at least 511 significant digits. pd->more
is set to 1 if this approximation is not exact (that is, the
accepted token contains additional non-zero digits beyond
those copied to pd->ds) and to 0 otherwise.
If the accepted token has the NAN(string) form, up to 511
characters from the string part are copied to pd->ds.
pd->ds is always terminated by a null byte, and pd->ndigits
is set to the length of the string stored in pd->ds.
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Standard C Library Functions stringtodecimal(3C)
On entry, *pc points to the beginning of a character string
buffer. The stringtodecimal() function reads characters
from this buffer until either enough characters are read to
delimit the accepted token (for example, a null character
marking the end of the string is found) or the limit of nmax
characters is reached. The filetodecimal() function reads
characters from the file *pf and stores them in the buffer.
The functodecimal() function reads characters one at a
time by calling the function (*pget)() and stores them in
the buffer; (*pget)() must return integer values in the
range -1 to 255, where -1 is interpreted as EOF and 0, ...,
255 are interpreted as unsigned char values. Both
filetodecimal() and functodecimal() read characters
until either enough characters are read to delimit the
accepted token, EOF is encountered, or the limit of nmax
characters is reached. These functions, therefore, typically
read one or more additional characters beyond the end of the
accepted token and attempt to push back any excess charac-
ters read. Provided that the punget argument is not NUL,
functodecimal() pushes back characters one at a time by
calling (*punget)(c), where c is an integer in the range 0
to 255 corresponding to a value previously read via
(*pget)(). After pushing back as many excess characters as
possible, filetodecimal() and functodecimal() store a
null byte in the buffer following the last character read
and not pushed back and set *pnread to the number of charac-
ters stored in the buffer prior to this null byte. Since
these functions can read up to nmax characters, the buffer
must be large enough to hold nmax ] 1.
On exit, *pc points to the next character in the buffer past
the last one that was accepted as part of the numeric token.
If no valid token is found, *pc is unchanged. If
filetodecimal() and functodecimal() successfully push
back all unused characters, *pc points to the null byte
stored in the buffer following the last character read and
not pushed back.
If the accepted token contains an exponent part, *pechar is
set to point to the position in the buffer where the first
character of the exponent field is stored. If the accepted
token does not contain an exponent part, *pechar is set to
NUL.
USAGE
If the IOWRT flag is set in *pf, filetodecimal() reads
characters directly from the file buffer until a null char-
acter is found. (The IOWRT flag should only be set when
filetodecimal() is called from sscanf(3C).) Otherwise,
filetodecimal() uses getcunlocked(3C), so it is not MT-
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Standard C Library Functions stringtodecimal(3C)
safe unless the caller holds the stream lock.
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
MT-Level MT-Safe with exceptions
SEE ALSO
ctype(3C), decimaltofloating(3C), getcunlocked(3C),
isspace(3C), localeconv(3C), scanf(3C), setlocale(3C),
strtod(3C), ungetc(3C), attributes(5)
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