1.\" $NetBSD: strtod.3,v 1.5 1995/12/28 08:52:49 thorpej Exp $ 2.\" 3.\" Copyright (c) 1990, 1991 The Regents of the University of California. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" the American National Standards Committee X3, on Information 8.\" Processing Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by the University of 21.\" California, Berkeley and its contributors. 22.\" 4. Neither the name of the University nor the names of its contributors 23.\" may be used to endorse or promote products derived from this software 24.\" without specific prior written permission. 25.\" 26.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36.\" SUCH DAMAGE. 37.\" 38.\" from: @(#)strtod.3 5.3 (Berkeley) 6/29/91 39.\" 40.Dd June 29, 1991 41.Dt STRTOD 3 42.Os 43.Sh NAME 44.Nm strtod 45.Nd convert 46.Tn ASCII 47string to double 48.Sh SYNOPSIS 49.Fd #include <stdlib.h> 50.Ft double 51.Fn strtod "const char *nptr" "char **endptr" 52.Sh DESCRIPTION 53The 54.Fn strtod 55function converts the initial portion of the string 56pointed to by 57.Fa nptr 58to 59.Em double 60representation. 61.Pp 62The expected form of the string is an optional plus (``+'') or minus 63sign (``-'') followed by a sequence of digits optionally containing 64a decimal-point character, optionally followed by an exponent. 65An exponent consists of an ``E'' or ``e'', followed by an optional plus 66or minus sign, followed by a sequence of digits. 67.Pp 68Leading white-space characters in the string (as defined by the 69.Xr isspace 3 70function) are skipped. 71.Sh RETURN VALUES 72The 73.Fn strtod 74function returns the converted value, if any. 75.Pp 76If 77.Fa endptr 78is not 79.Dv NULL , 80a pointer to the character after the last character used 81in the conversion is stored in the location referenced by 82.Fa endptr . 83.Pp 84If no conversion is performed, zero is returned and the value of 85.Fa nptr 86is stored in the location referenced by 87.Fa endptr . 88.Pp 89If the correct value would cause overflow, plus or minus 90.Dv HUGE_VAL 91is returned (according to the sign of the value), and 92.Dv ERANGE 93is stored in 94.Va errno . 95If the correct value would cause underflow, zero is 96returned and 97.Dv ERANGE 98is stored in 99.Va errno . 100.Sh ERRORS 101.Bl -tag -width Er 102.It Bq Er ERANGE 103Overflow or underflow occurred. 104.Sh SEE ALSO 105.Xr atof 3 , 106.Xr atoi 3 , 107.Xr atol 3 , 108.Xr strtol 3 , 109.Xr strtoul 3 110.Sh STANDARDS 111The 112.Fn strtod 113function 114conforms to 115.St -ansiC . 116