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32.\"	$OpenBSD: strtod.3,v 1.8 2003/06/02 20:18:38 millert Exp $
33.\"
34.Dd $Mdocdate: February 9 2014 $
35.Dt STRTOD 3
36.Os
37.Sh NAME
38.Nm strtod , strtof
39.Nd convert
40.Tn ASCII
41string to floating point
42.Sh SYNOPSIS
43.Fd #include <stdlib.h>
44.Ft double
45.Fn strtod "const char *nptr" "char **endptr"
46.Ft float
47.Fn strtof "const char *nptr" "char **endptr"
48.Sh DESCRIPTION
49These conversion functions convert the initial portion of the string pointed
50to by
51.Fa nptr
52to
53.Li double
54or
55.Li float
56representation, respectively.
57.Pp
58The expected form of the string is an optional plus
59.Pq Ql +
60or minus sign
61.Pq Ql -
62followed by a sequence of digits optionally containing
63a decimal-point character, optionally followed by an exponent.
64An exponent consists of an
65.Sq E
66or
67.Sq e ,
68followed by an optional plus or minus sign, followed by a sequence of digits.
69.Pp
70Leading whitespace characters in the string (as defined by the
71.Xr isspace 3
72function) are skipped.
73.Sh RETURN VALUES
74The
75.Fn strtod
76and
77.Fn strtof
78functions return the converted value, if any.
79.Pp
80If
81.Fa endptr
82is not
83.Dv NULL ,
84a pointer to the character after the last character used
85in the conversion is stored in the location referenced by
86.Fa endptr .
87.Pp
88If no conversion is performed, zero is returned and the value of
89.Fa nptr
90is stored in the location referenced by
91.Fa endptr .
92.Pp
93If the correct value would cause overflow, plus or minus
94.Dv HUGE_VAL
95is returned (according to the sign of the value), and
96.Er ERANGE
97is stored in
98.Va errno .
99If the correct value would cause underflow, zero is returned and
100.Er ERANGE
101is stored in
102.Va errno .
103.Sh ERRORS
104.Bl -tag -width Er
105.It Bq Er ERANGE
106Overflow or underflow occurred.
107.El
108.Sh SEE ALSO
109.Xr atof 3 ,
110.Xr atoi 3 ,
111.Xr atol 3 ,
112.Xr strtol 3 ,
113.Xr strtoul 3
114.Sh STANDARDS
115The
116.Fn strtod
117function conforms to
118.St -ansiC .
119.Sh HISTORY
120The
121.Fn strtof
122function was added to
123.Mx
124in 2013.
125
126