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.\" %sccs.include.redist.man% 9.\" 10.\" @(#)strtod.3 8.1 (Berkeley) 06/04/93 11.\" 12.Dd 13.Dt STRTOD 3 14.Os 15.Sh NAME 16.Nm strtod 17.Nd convert 18.Tn ASCII 19string to double 20.Sh SYNOPSIS 21.Fd #include <stdlib.h> 22.Ft double 23.Fn strtod "const char *nptr" "char **endptr" 24.Sh DESCRIPTION 25The 26.Fn strtod 27function converts the initial portion of the string 28pointed to by 29.Fa nptr 30to 31.Em double 32representation. 33.Pp 34The expected form of the string is an optional plus (``+'') or minus 35sign (``\-'') followed by a sequence of digits optionally containing 36a decimal-point character, optionally followed by an exponent. 37An exponent consists of an ``E'' or ``e'', followed by an optional plus 38or minus sign, followed by a sequence of digits. 39.Pp 40Leading white-space characters in the string (as defined by the 41.Xr isspace 3 42function) are skipped. 43.Sh RETURN VALUES 44The 45.Fn strtod 46function returns the converted value, if any. 47.Pp 48If 49.Fa endptr 50is not 51.Dv NULL , 52a pointer to the character after the last character used 53in the conversion is stored in the location referenced by 54.Fa endptr . 55.Pp 56If no conversion is performed, zero is returned and the value of 57.Fa nptr 58is stored in the location referenced by 59.Fa endptr . 60.Pp 61If the correct value would cause overflow, plus or minus 62.Dv HUGE_VAL 63is returned (according to the sign of the value), and 64.Dv ERANGE 65is stored in 66.Va errno . 67If the correct value would cause underflow, zero is 68returned and 69.Dv ERANGE 70is stored in 71.Va errno . 72.Sh ERRORS 73.Bl -tag -width [ERANGE] 74.It Bq Er ERANGE 75Overflow or underflow occurred. 76.Sh SEE ALSO 77.Xr atof 3 , 78.Xr atoi 3 , 79.Xr atol 3 , 80.Xr strtol 3 , 81.Xr strtoul 3 82.Sh STANDARDS 83The 84.Fn strtod 85function 86conforms to 87.St -ansiC . 88.Sh AUTHORS 89The author of this software is David M. Gay. 90.Pp 91Copyright (c) 1991 by AT&T. 92.Pp 93Permission to use, copy, modify, and distribute this software for any 94purpose without fee is hereby granted, provided that this entire notice 95is included in all copies of any software which is or includes a copy 96or modification of this software and in all copies of the supporting 97documentation for such software. 98.Pp 99THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED 100WARRANTY. IN PARTICULAR, NEITHER THE AUTHOR NOR AT&T MAKES ANY 101REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY 102OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE. 103.Pp 104Contact your vendor for a free copy of the source code to 105.Fn strtod 106and accompanying functions. 107