1 .TH ATOF 3
2 .SH NAME
3 atof, atoi, atol, atoll, charstod, strtod, strtol, strtoll, strtoul, strtoull \- convert text to numbers
4 .SH SYNOPSIS
5 .B #include <u.h>
6 .br
7 .B #include <libc.h>
8 .PP
9 .nf
10 .ta \w'\fLdouble 'u
11 .B
12 double	atof(char *nptr)
13 .PP
14 .B
15 int	atoi(char *nptr)
16 .PP
17 .B
18 long	atol(char *nptr)
19 .PP
20 .B
21 vlong	atoll(char *nptr)
22 .PP
23 .B
24 double	charstod(int (*f)(void *), void *a)
25 .PP
26 .B
27 double	strtod(char *nptr, char **rptr)
28 .PP
29 .B
30 long	strtol(char *nptr, char **rptr, int base)
31 .PP
32 .B
33 vlong	strtoll(char *nptr, char **rptr, int base)
34 .PP
35 .B
36 ulong	strtoul(char *nptr, char **rptr, int base)
37 .PP
38 .B
39 vlong	strtoull(char *nptr, char **rptr, int base)
40 .fi
41 .SH DESCRIPTION
42 .IR Atof ,
43 .IR atoi ,
44 .IR atol ,
45 and
46 .I atoll
47 convert a string pointed to by
48 .I nptr
49 to floating, integer, long integer, and long long integer
50 .RB ( vlong )
51 representation respectively.
52 The first unrecognized character ends the string.
53 Leading C escapes are understood, as in
54 .I strtol
55 with
56 .I base
57 zero (described below).
58 .PP
59 .I Atof
60 recognizes an optional string of tabs and spaces,
61 then an optional sign, then
62 a string of digits optionally containing a decimal
63 point, then an optional 
64 .L e
65 or 
66 .L E
67 followed
68 by an optionally signed integer.
69 .PP
70 .I Atoi
71 and
72 .I atol
73 recognize an optional string of tabs and spaces,
74 then an optional sign, then a string of
75 decimal digits.
76 .PP
77 .IR Strtod ,
78 .IR strtol ,
79 .IR strtoll ,
80 .IR strtoul ,
81 and
82 .I strtoull
83 behave similarly to 
84 .I atof
85 and
86 .I atol
87 and, if
88 .I rptr
89 is not zero, set
90 .I *rptr
91 to point to the input character
92 immediately after the string converted.
93 .PP
94 .IR Strtol ,
95 .IR strtoll ,
96 .IR strtoul ,
97 and
98 .IR strtoull
99 interpret the digit string in the specified
100 .IR base ,
101 from 2 to 36,
102 each digit being less than the base.
103 Digits with value over 9 are represented by letters,
104 a-z or A-Z.
105 If
106 .I base
107 is 0, the input is interpreted as an integral constant in
108 the style of C (with no suffixed type indicators):
109 numbers are octal if they begin with
110 .LR 0 ,
111 hexadecimal if they begin with
112 .L 0x
113 or
114 .LR 0X ,
115 otherwise decimal.
116 .PP
117 .I Charstod
118 interprets floating point numbers in the manner of
119 .IR atof ,
120 but gets successive characters by calling
121 .BR (*\fIf\fP)(a) .
122 The last call to
123 .I f
124 terminates the scan, so it must have returned a character that
125 is not a legal continuation of a number.
126 Therefore, it may be necessary to back up the input stream one character
127 after calling
128 .IR charstod .
129 .SH SOURCE
130 .B \*9/src/lib9
131 .SH SEE ALSO
132 .MR fscanf (3)
133 .SH DIAGNOSTICS
134 Zero is returned if the beginning of the input string is not
135 interpretable as a number; even in this case,
136 .I rptr
137 will be updated.
138 .br
139 These routines set
140 .IR errstr .
141 .SH BUGS
142 .I Atoi
143 and
144 .I atol
145 accept octal and hexadecimal numbers in the style of C,
146 contrary to the ANSI specification.
147 .PP
148 .IR Atof ,
149 .IR strtod ,
150 .IR strtol ,
151 .IR strtoul ,
152 .IR strtoll ,
153 and
154 .IR strtoull
155 are not provided:
156 they are expected to be provided by the underlying system.
157 .PP
158 Because they are implemented in the fmt library,
159 .I charstod
160 and
161 .I strtod
162 are preprocessor macros defined as
163 .I fmtcharstod
164 and
165 .IR fmtstrtod .
166 .PP
167 To avoid name conflicts with the underlying system,
168 .IR atoi ,
169 .IR atol ,
170 and
171 .I atoll
172 are preprocessor macros defined as
173 .IR p9atoi ,
174 .IR p9atol ,
175 and
176 .IR p9atoll ;
177 see
178 .MR intro (3) .