1.\" Copyright (c) 1990, 1991 The Regents of the University of California. 2.\" 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. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" $OpenBSD: strtod.3,v 1.8 2003/06/02 20:18:38 millert Exp $ 33.\" 34.Dd June 29, 1991 35.Dt STRTOD 3 36.Os 37.Sh NAME 38.Nm strtod 39.Nd convert 40.Tn ASCII 41string to double 42.Sh SYNOPSIS 43.Fd #include <stdlib.h> 44.Ft double 45.Fn strtod "const char *nptr" "char **endptr" 46.Sh DESCRIPTION 47The 48.Fn strtod 49function converts the initial portion of the string pointed to by 50.Fa nptr 51to 52.Li double 53representation. 54.Pp 55The expected form of the string is an optional plus 56.Pq Ql + 57or minus sign 58.Pq Ql - 59followed by a sequence of digits optionally containing 60a decimal-point character, optionally followed by an exponent. 61An exponent consists of an 62.Sq E 63or 64.Sq e , 65followed by an optional plus or minus sign, followed by a sequence of digits. 66.Pp 67Leading whitespace characters in the string (as defined by the 68.Xr isspace 3 69function) are skipped. 70.Sh RETURN VALUES 71The 72.Fn strtod 73function returns the converted value, if any. 74.Pp 75If 76.Fa endptr 77is not 78.Dv NULL , 79a pointer to the character after the last character used 80in the conversion is stored in the location referenced by 81.Fa endptr . 82.Pp 83If no conversion is performed, zero is returned and the value of 84.Fa nptr 85is stored in the location referenced by 86.Fa endptr . 87.Pp 88If the correct value would cause overflow, plus or minus 89.Dv HUGE_VAL 90is returned (according to the sign of the value), and 91.Er ERANGE 92is stored in 93.Va errno . 94If the correct value would cause underflow, zero is returned and 95.Er ERANGE 96is stored in 97.Va errno . 98.Sh ERRORS 99.Bl -tag -width Er 100.It Bq Er ERANGE 101Overflow or underflow occurred. 102.El 103.Sh SEE ALSO 104.Xr atof 3 , 105.Xr atoi 3 , 106.Xr atol 3 , 107.Xr strtol 3 , 108.Xr strtoul 3 109.Sh STANDARDS 110The 111.Fn strtod 112function conforms to 113.St -ansiC . 114