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.\" 38.Dd June 4, 1993 39.Dt STRTOD 3 40.Os 41.Sh NAME 42.Nm strtod 43.Nd convert 44.Tn ASCII 45string to double 46.Sh SYNOPSIS 47.Fd #include <stdlib.h> 48.Ft double 49.Fn strtod "const char *nptr" "char **endptr" 50.Sh DESCRIPTION 51The 52.Fn strtod 53function converts the initial portion of the string 54pointed to by 55.Fa nptr 56to 57.Em double 58representation. 59.Pp 60The expected form of the string is an optional plus (``+'') or minus 61sign (``\-'') followed by a sequence of digits optionally containing 62a decimal-point character, optionally followed by an exponent. 63An exponent consists of an ``E'' or ``e'', followed by an optional plus 64or minus sign, followed by a sequence of digits. 65.Pp 66Leading white-space characters in the string (as defined by the 67.Xr isspace 3 68function) are skipped. 69.Sh RETURN VALUES 70The 71.Fn strtod 72function returns the converted value, if any. 73.Pp 74If 75.Fa endptr 76is not 77.Dv NULL , 78a pointer to the character after the last character used 79in the conversion is stored in the location referenced by 80.Fa endptr . 81.Pp 82If no conversion is performed, zero is returned and the value of 83.Fa nptr 84is stored in the location referenced by 85.Fa endptr . 86.Pp 87If the correct value would cause overflow, plus or minus 88.Dv HUGE_VAL 89is returned (according to the sign of the value), and 90.Dv ERANGE 91is stored in 92.Va errno . 93If the correct value would cause underflow, zero is 94returned and 95.Dv ERANGE 96is stored in 97.Va errno . 98.Sh ERRORS 99.Bl -tag -width [ERANGE] 100.It Bq Er ERANGE 101Overflow or underflow occurred. 102.Sh SEE ALSO 103.Xr atof 3 , 104.Xr atoi 3 , 105.Xr atol 3 , 106.Xr strtol 3 , 107.Xr strtoul 3 108.Sh STANDARDS 109The 110.Fn strtod 111function 112conforms to 113.St -ansiC . 114.Sh AUTHORS 115The author of this software is David M. Gay. 116.Pp 117Copyright (c) 1991 by AT&T. 118.Pp 119Permission to use, copy, modify, and distribute this software for any 120purpose without fee is hereby granted, provided that this entire notice 121is included in all copies of any software which is or includes a copy 122or modification of this software and in all copies of the supporting 123documentation for such software. 124.Pp 125THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED 126WARRANTY. IN PARTICULAR, NEITHER THE AUTHOR NOR AT&T MAKES ANY 127REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY 128OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE. 129.Pp 130Contact your vendor for a free copy of the source code to 131.Fn strtod 132and accompanying functions. 133