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.\" $FreeBSD$ 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 SYNOPSIS 48.Fd #include <stdlib.h> 49.Ft double 50.Fn strtod "const char *nptr" "char **endptr" 51.Sh DESCRIPTION 52The 53.Fn strtod 54function converts the initial portion of the string 55pointed to by 56.Fa nptr 57to 58.Em double 59representation. 60.Pp 61The expected form of the string is an optional plus (``+'') or minus 62sign (``\-'') followed by a sequence of digits optionally containing 63a decimal-point character, optionally followed by an exponent. 64An exponent consists of an ``E'' or ``e'', followed by an optional plus 65or minus sign, followed by a sequence of digits. 66.Pp 67Leading white-space 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.Dv ERANGE 92is stored in 93.Va errno . 94If the correct value would cause underflow, zero is 95returned and 96.Dv ERANGE 97is stored in 98.Va errno . 99.Sh ERRORS 100.Bl -tag -width [ERANGE] 101.It Bq Er ERANGE 102Overflow or underflow occurred. 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 113conforms to 114.St -ansiC . 115.Sh AUTHORS 116The author of this software is 117.An David M. Gay . 118.Pp 119Copyright (c) 1991 by AT&T. 120.Pp 121Permission to use, copy, modify, and distribute this software for any 122purpose without fee is hereby granted, provided that this entire notice 123is included in all copies of any software which is or includes a copy 124or modification of this software and in all copies of the supporting 125documentation for such software. 126.Pp 127THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED 128WARRANTY. IN PARTICULAR, NEITHER THE AUTHOR NOR AT&T MAKES ANY 129REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY 130OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE. 131.Pp 132Contact your vendor for a free copy of the source code to 133.Fn strtod 134and accompanying functions. 135