1 .TH FMTSTRTOD 3
2 .SH NAME
3 fmtstrtod, fmtcharstod \ - convert text to numbers
4 .SH SYNOPSIS
5 .B #include <utf.h>
6 .br
7 .B #include <fmt.h>
8 .PP
9 .PP
10 .B
11 double	fmtstrtod(char *nptr, char **rptr)
12 .PP
13 .B
14 double	fmtcharstod(int (*f)(void *), void *a)
15 .SH DESCRIPTION
16 .I Fmtstrtod
17 converts a string pointed to by
18 .I nptr
19 to floating point representation and, if
20 .I rptr
21 is not zero, sets
22 .I *rptr
23 to point to the input character immediately after the string converted.
24 .I Fmtstrtod
25 recognizes an optional string of tabs and spaces,
26 then an optional sign, then a string of digits optionally
27 containing a decimal point, then an optional 
28 .L e
29 or
30 .L E
31 followed by an optionally signed integer.
32 .PP
33 .PP
34 .I Fmtcharstod
35 interprets floating point numbers in the manner of
36 .IR atof ,
37 but gets successive characters by calling
38 .BR (*\fIf\fP)(a) .
39 The last call to
40 .I f
41 terminates the scan, so it must have returned a character that
42 is not a legal continuation of a number.
43 Therefore, it may be necessary to back up the input stream one character
44 after calling
45 .IR fmtcharstod .
46 .SH SOURCE
47 .B https://9fans.github.io/plan9port/unix
48 .SH SEE ALSO
49 .IR fscanf (3)
50 .SH DIAGNOSTICS
51 Zero is returned if the beginning of the input string is not interpretable
52 as a number; even in this case,
53 .I rptr
54 will be updated.