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diff --git a/man3/strtod.3 b/man3/strtod.3 new file mode 100644 index 0000000..23e7578 --- /dev/null +++ b/man3/strtod.3 @@ -0,0 +1,206 @@ +'\" t +.\" Copyright (c) 1990, 1991 The Regents of the University of California. +.\" All rights reserved. +.\" +.\" This code is derived from software contributed to Berkeley by +.\" the American National Standards Committee X3, on Information +.\" Processing Systems. +.\" +.\" SPDX-License-Identifier: BSD-4-Clause-UC +.\" +.\" @(#)strtod.3 5.3 (Berkeley) 6/29/91 +.\" +.\" Modified Sun Aug 21 17:16:22 1994 by Rik Faith (faith@cs.unc.edu) +.\" Modified Sat May 04 19:34:31 MET DST 1996 by Michael Haardt +.\" (michael@cantor.informatik.rwth-aachen.de) +.\" Added strof, strtold, aeb, 2001-06-07 +.\" +.TH strtod 3 2023-07-20 "Linux man-pages 6.05.01" +.SH NAME +strtod, strtof, strtold \- convert ASCII string to floating-point number +.SH LIBRARY +Standard C library +.RI ( libc ", " \-lc ) +.SH SYNOPSIS +.nf +.B #include <stdlib.h> +.PP +.BI "double strtod(const char *restrict " nptr ", char **restrict " endptr ); +.BI "float strtof(const char *restrict " nptr ", char **restrict " endptr ); +.BI "long double strtold(const char *restrict " nptr \ +", char **restrict " endptr ); +.fi +.PP +.RS -4 +Feature Test Macro Requirements for glibc (see +.BR feature_test_macros (7)): +.RE +.PP +.BR strtof (), +.BR strtold (): +.nf + _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L +.fi +.SH DESCRIPTION +The +.BR strtod (), +.BR strtof (), +and +.BR strtold () +functions convert the initial portion of the string pointed to by +.I nptr +to +.IR double , +.IR float , +and +.I long double +representation, respectively. +.PP +The expected form of the (initial portion of the) string is +optional leading white space as recognized by +.BR isspace (3), +an optional plus (\[aq]+\[aq]) or minus sign (\[aq]\-\[aq]) and then either +(i) a decimal number, or (ii) a hexadecimal number, +or (iii) an infinity, or (iv) a NAN (not-a-number). +.PP +A +.I "decimal number" +consists of a nonempty sequence of decimal digits +possibly containing a radix character (decimal point, locale-dependent, +usually \[aq].\[aq]), optionally followed by a decimal exponent. +A decimal exponent consists of an \[aq]E\[aq] or \[aq]e\[aq], followed by an +optional plus or minus sign, followed by a nonempty sequence of +decimal digits, and indicates multiplication by a power of 10. +.PP +A +.I "hexadecimal number" +consists of a "0x" or "0X" followed by a nonempty sequence of +hexadecimal digits possibly containing a radix character, +optionally followed by a binary exponent. +A binary exponent +consists of a \[aq]P\[aq] or \[aq]p\[aq], followed by an optional +plus or minus sign, followed by a nonempty sequence of +decimal digits, and indicates multiplication by a power of 2. +At least one of radix character and binary exponent must be present. +.PP +An +.I infinity +is either "INF" or "INFINITY", disregarding case. +.PP +A +.I NAN +is "NAN" (disregarding case) optionally followed by a string, +.IR (n-char-sequence) , +where +.I n-char-sequence +specifies in an implementation-dependent +way the type of NAN (see NOTES). +.SH RETURN VALUE +These functions return the converted value, if any. +.PP +If +.I endptr +is not NULL, +a pointer to the character after the last character used in the conversion +is stored in the location referenced by +.IR endptr . +.PP +If no conversion is performed, zero is returned and (unless +.I endptr +is null) the value of +.I nptr +is stored in the location referenced by +.IR endptr . +.PP +If the correct value would cause overflow, plus or minus +.BR HUGE_VAL , +.BR HUGE_VALF , +or +.B HUGE_VALL +is returned (according to the return type and sign of the value), +and +.B ERANGE +is stored in +.IR errno . +.PP +If the correct value would cause underflow, +a value with magnitude no larger than +.BR DBL_MIN , +.BR FLT_MIN , +or +.B LDBL_MIN +is returned and +.B ERANGE +is stored in +.IR errno . +.SH ERRORS +.TP +.B ERANGE +Overflow or underflow occurred. +.SH ATTRIBUTES +For an explanation of the terms used in this section, see +.BR attributes (7). +.TS +allbox; +lbx lb lb +l l l. +Interface Attribute Value +T{ +.na +.nh +.BR strtod (), +.BR strtof (), +.BR strtold () +T} Thread safety MT-Safe locale +.TE +.sp 1 +.SH VERSIONS +In the glibc implementation, the +.I n-char-sequence +that optionally follows "NAN" +is interpreted as an integer number +(with an optional '0' or '0x' prefix to select base 8 or 16) +that is to be placed in the +mantissa component of the returned value. +.\" From glibc 2.8's stdlib/strtod_l.c: +.\" We expect it to be a number which is put in the +.\" mantissa of the number. +.\" It looks as though at least FreeBSD (according to the manual) does +.\" something similar. +.\" C11 says: "An implementation may use the n-char sequence to determine +.\" extra information to be represented in the NaN's significant." +.SH STANDARDS +C11, POSIX.1-2008. +.SH HISTORY +.TP +.BR strtod () +C89, POSIX.1-2001. +.TP +.BR strtof () +.TQ +.BR strtold () +C99, POSIX.1-2001. +.SH NOTES +Since +0 can legitimately be returned +on both success and failure, the calling program should set +.I errno +to 0 before the call, +and then determine if an error occurred by checking whether +.I errno +has a nonzero value after the call. +.SH EXAMPLES +See the example on the +.BR strtol (3) +manual page; +the use of the functions described in this manual page is similar. +.SH SEE ALSO +.BR atof (3), +.BR atoi (3), +.BR atol (3), +.BR nan (3), +.BR nanf (3), +.BR nanl (3), +.BR strfromd (3), +.BR strtol (3), +.BR strtoul (3) |