1.\" Copyright (c) 1991 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)atof.3 6.3 (Berkeley) 04/19/91 7.\" 8.Dd 9.Dt ATOF 3 10.Os 11.Sh NAME 12.Nm atof 13.Nd convert 14.Tn ASCII 15string to double 16.Sh SYNOPSIS 17.Fd #include <stdlib.h> 18.Ft double 19.Fn atof "const char *nptr" 20.Sh DESCRIPTION 21The 22.Fn atof 23function converts the initial portion of the string pointed to by 24.Ar nptr 25to 26.Ar double 27representation. 28.Pp 29It is equivalent to: 30.Bd -literal -offset indent 31strtod(nptr, (char **)NULL); 32.Ed 33.Sh SEE ALSO 34.Xr atoi 3 , 35.Xr atol 3 , 36.Xr strtod 3 , 37.Xr strtol 3 , 38.Xr strtoul 3 39.Sh STANDARDS 40The 41.Fn atof 42function conforms to 43.St -ansiC . 44.Sh BUGS 45This manual page represents intent instead of actual practice. 46While it is intended that 47.Fn atof 48be implemented using 49.Xr strtod 3 , 50this has not yet happened. 51In the current system, 52.Fn atof 53translates a string in the following form to a double: a string of 54leading white space, possibly followed by a sign (``+'' or ``-''), 55followed by a digit string which may contain one decimal point (``.''), 56which may be followed by either of the exponent flags (``E'' or ``e''), 57and lastly, followed by a signed or unsigned integer. 58