xref: /netbsd-src/lib/libc/stdlib/strtol.3 (revision 448e711c7835101c94f75b7ebddf58046df58290)
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5.\" Chris Torek and the American National Standards Committee X3,
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36.\"     from: @(#)strtol.3	5.3 (Berkeley) 6/29/91
37.\"	$Id: strtol.3,v 1.3 1993/11/29 22:07:20 jtc Exp $
38.\"
39.Dd June 29, 1991
40.Dt STRTOL 3
41.Os
42.Sh NAME
43.Nm strtol
44.Nd convert string value to a long integer
45.Sh SYNOPSIS
46.Fd #include <stdlib.h>
47.Fd #include <limits.h>
48.Ft long
49.Fn strtol "char *nptr" "char **endptr" "int base"
50.Sh DESCRIPTION
51The
52.Fn strtol
53function
54converts the string in
55.Fa nptr
56to a
57.Em long
58value according to the given
59.Fa base ,
60which must be between 2 and 36 inclusive,
61or be the special value 0.
62.Pp
63The string may begin with an arbitrary amount of white space
64(as determined by
65.Xr isspace 3 )
66followed by a single optional
67.Ql +
68or
69.Ql -
70sign.
71If
72.Fa base
73is zero or 16,
74the string may then include a
75.Ql 0x
76prefix,
77and the number will be read in base 16; otherwise, a zero
78.Fa base
79is taken as 10 (decimal) unless the next character is
80.Ql 0 ,
81in which case it is taken as 8 (octal).
82.Pp
83The remainder of the string is converted to a
84.Em long
85value in the obvious manner,
86stopping at the first character which is not a valid digit
87in the given base.
88(In bases above 10, the letter
89.Ql A
90in either upper or lower case
91represents 10,
92.Ql B
93represents 11, and so forth, with
94.Ql Z
95representing 35.)
96.Pp
97If
98.Fa endptr
99is non nil,
100.Fn strtol
101stores the address of the first invalid character in
102.Fa *endptr .
103If there were no digits at all, however,
104.Fn strtol
105stores the original value of
106.Fa nptr
107in
108.Fa *endptr .
109(Thus, if
110.Fa *nptr
111is not
112.Ql \e0
113but
114.Fa **endptr
115is
116.Ql \e0
117on return, the entire string was valid.)
118.Sh RETURN VALUES
119The
120.Fn strtol
121function
122returns the result of the conversion,
123unless the value would underflow or overflow.
124If an underflow occurs,
125.Fn strtol
126returns
127.Dv LONG_MIN .
128If an overflow occurs,
129.Fn strtol
130returns
131.Dv LONG_MAX .
132In both cases,
133.Va errno
134is set to
135.Er ERANGE .
136.Sh ERRORS
137.Bl -tag -width Er
138.It Bq Er ERANGE
139The given string was out of range; the value converted has been clamped.
140.El
141.Sh SEE ALSO
142.Xr atof 3 ,
143.Xr atoi 3 ,
144.Xr atol 3 ,
145.Xr strtod 3 ,
146.Xr strtoul 3
147.Sh STANDARDS
148The
149.Fn strtol
150function
151conforms to
152.St -ansiC .
153.Sh BUGS
154Ignores the current locale.
155