1.\" Copyright (c) 1990, 1991 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)strtod.3 5.2 (Berkeley) 04/19/91 7.\" 8.Dd 9.Dt STRTOD 3 10.Os 11.Sh NAME 12.Nm strtod 13.Nd convert 14.Tn ASCII 15string to double 16.Sh SYNOPSIS 17.Fd #include <stdlib.h> 18.Ft double 19.Fn strtod "const char *nptr" "char **endptr" 20.Sh DESCRIPTION 21The 22.Fn strtod 23function converts the initial portion of the string 24pointed to by 25.Fa nptr 26to 27.Em double 28representation. 29.Pp 30The expected form of the string is an optional plus (``+'') or minus 31sign (``-'') followed by a sequence of digits optionally containing 32a decimal-point character, optionally followed by an exponent. 33An exponent consists of an ``E'' or ``e'', followed by an optional plus 34or minus sign, followed by a sequence of digits. 35.Pp 36Leading white-space characters in the string (as defined by the 37.Xr isspace 3 38function) are skipped. 39.Sh RETURN VALUES 40The 41.Fn strtod 42function returns the converted value, if any. 43.Pp 44If 45.Fa endptr 46is not 47.Dv NULL , 48a pointer to the character after the last character used 49in the conversion is stored in the location referenced by 50.Fa endptr . 51.Pp 52If no conversion is performed, zero is returned and the value of 53.Fa nptr 54is stored in the location referenced by 55.Fa endptr . 56.Pp 57If the correct value would cause overflow, plus or minus 58.Dv HUGE_VAL 59is returned (according to the sign of the value), and 60.Dv ERANGE 61is stored in 62.Va errno . 63If the correct value would cause underflow, zero is 64returned and 65.Dv ERANGE 66is stored in 67.Va errno . 68.Sh ERRORS 69.Bl -tag -width [ERANGE] 70.It Bq Er ERANGE 71Overflow or underflow occurred. 72.Sh SEE ALSO 73.Xr atof 3 , 74.Xr atoi 3 , 75.Xr atol 3 , 76.Xr strtol 3 , 77.Xr strtoul 3 78.Sh STANDARDS 79The 80.Fn strtod 81function 82conforms to 83.St -ansiC . 84.Sh BUGS 85This manual page represents intent instead of actual practice. 86The 87.Fn strtod 88function is not currently available. 89