1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the American National Standards Committee X3, on Information 6.\" Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" @(#)strtod.3 8.1 (Berkeley) 6/4/93 37.\" $FreeBSD: src/lib/libc/stdlib/strtod.3,v 1.4.2.7 2001/12/14 18:33:58 ru Exp $ 38.\" 39.Dd June 4, 1993 40.Dt STRTOD 3 41.Os 42.Sh NAME 43.Nm strtod 44.Nd convert 45.Tn ASCII 46string to double 47.Sh LIBRARY 48.Lb libc 49.Sh SYNOPSIS 50.In stdlib.h 51.Ft double 52.Fn strtod "const char *nptr" "char **endptr" 53.Sh DESCRIPTION 54The 55.Fn strtod 56function converts the initial portion of the string 57pointed to by 58.Fa nptr 59to 60.Em double 61representation. 62.Pp 63The expected form of the string is an optional plus (``+'') or minus 64sign (``\-'') followed by a sequence of digits optionally containing 65a decimal-point character, optionally followed by an exponent. 66An exponent consists of an ``E'' or ``e'', followed by an optional plus 67or minus sign, followed by a sequence of digits. 68.Pp 69Leading white-space characters in the string (as defined by the 70.Xr isspace 3 71function) are skipped. 72.Sh RETURN VALUES 73The 74.Fn strtod 75function returns the converted value, if any. 76.Pp 77If 78.Fa endptr 79is not 80.Dv NULL , 81a pointer to the character after the last character used 82in the conversion is stored in the location referenced by 83.Fa endptr . 84.Pp 85If no conversion is performed, zero is returned and the value of 86.Fa nptr 87is stored in the location referenced by 88.Fa endptr . 89.Pp 90If the correct value would cause overflow, plus or minus 91.Dv HUGE_VAL 92is returned (according to the sign of the value), and 93.Er ERANGE 94is stored in 95.Va errno . 96If the correct value would cause underflow, zero is 97returned and 98.Er ERANGE 99is stored in 100.Va errno . 101.Sh ERRORS 102.Bl -tag -width Er 103.It Bq Er ERANGE 104Overflow or underflow occurred. 105.El 106.Sh SEE ALSO 107.Xr atof 3 , 108.Xr atoi 3 , 109.Xr atol 3 , 110.Xr strtol 3 , 111.Xr strtoul 3 112.Sh STANDARDS 113The 114.Fn strtod 115function 116conforms to 117.St -isoC . 118.Sh AUTHORS 119The author of this software is 120.An David M. Gay . 121.Pp 122Copyright (c) 1991 by AT&T. 123.Pp 124Permission to use, copy, modify, and distribute this software for any 125purpose without fee is hereby granted, provided that this entire notice 126is included in all copies of any software which is or includes a copy 127or modification of this software and in all copies of the supporting 128documentation for such software. 129.Pp 130THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED 131WARRANTY. IN PARTICULAR, NEITHER THE AUTHOR NOR AT&T MAKES ANY 132REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY 133OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE. 134.Pp 135Contact your vendor for a free copy of the source code to 136.Fn strtod 137and accompanying functions. 138