1.\" $NetBSD: strtod.3,v 1.10 2001/09/16 01:31:53 wiz Exp $ 2.\" 3.\" Copyright (c) 1990, 1991, 1993 4.\" The Regents of the University of California. 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 8.1 (Berkeley) 6/4/93 39.\" 40.Dd March 21, 2001 41.Dt STRTOD 3 42.Os 43.Sh NAME 44.Nm strtod 45.Nd convert 46.Tn ASCII 47string to double 48.Sh LIBRARY 49.Lb libc 50.Sh SYNOPSIS 51.Fd #include <stdlib.h> 52.Ft double 53.Fn strtod "const char * restrict nptr" "char ** restrict endptr" 54.Sh DESCRIPTION 55The 56.Fn strtod 57function converts the initial portion of the string 58pointed to by 59.Fa nptr 60to 61.Em double 62representation. 63.Pp 64The expected form of the string is an optional plus (``+'') or minus 65sign (``\-'') followed by a sequence of digits optionally containing 66a decimal-point character, optionally followed by an exponent. 67An exponent consists of an ``E'' or ``e'', followed by an optional plus 68or minus sign, followed by a sequence of digits. 69.Pp 70Leading white-space characters in the string (as defined by the 71.Xr isspace 3 72function) are skipped. 73.Sh RETURN VALUES 74The 75.Fn strtod 76function returns the converted value, if any. 77.Pp 78If 79.Fa endptr 80is not 81.Dv NULL , 82a pointer to the character after the last character used 83in the conversion is stored in the location referenced by 84.Fa endptr . 85.Pp 86If no conversion is performed, zero is returned and the value of 87.Fa nptr 88is stored in the location referenced by 89.Fa endptr . 90.Pp 91If the correct value would cause overflow, plus or minus 92.Dv HUGE_VAL 93is returned (according to the sign of the value), and 94.Dv ERANGE 95is stored in 96.Va errno . 97If the correct value would cause underflow, zero is 98returned and 99.Dv ERANGE 100is stored in 101.Va errno . 102.Sh ERRORS 103.Bl -tag -width Er 104.It Bq Er ERANGE 105Overflow or underflow occurred. 106.El 107.Sh SEE ALSO 108.Xr atof 3 , 109.Xr atoi 3 , 110.Xr atol 3 , 111.Xr strtol 3 , 112.Xr strtoul 3 113.Sh STANDARDS 114The 115.Fn strtod 116function 117conforms to 118.St -ansiC . 119