xref: /freebsd/lib/libc/stdlib/strtol.3 (revision 23f282aa31e9b6fceacd449020e936e98d6f2298)
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36.\"     @(#)strtol.3	8.1 (Berkeley) 6/4/93
37.\" $FreeBSD$
38.\"
39.Dd June 4, 1993
40.Dt STRTOL 3
41.Os
42.Sh NAME
43.Nm strtol, strtoq
44.Nd convert string value to a long or quad_t integer
45.Sh LIBRARY
46.Lb libc
47.Sh SYNOPSIS
48.Fd #include <stdlib.h>
49.Fd #include <limits.h>
50.Ft long
51.Fn strtol "const char *nptr" "char **endptr" "int base"
52
53.Fd #include <sys/types.h>
54.Fd #include <stdlib.h>
55.Fd #include <limits.h>
56.Ft quad_t
57.Fn strtoq "const char *nptr" "char **endptr" "int base"
58.Sh DESCRIPTION
59The
60.Fn strtol
61function
62converts the string in
63.Fa nptr
64to a
65.Em long
66value.
67The
68.Fn strtoq
69function
70converts the string in
71.Fa nptr
72to a
73.Em quad_t
74value.
75The conversion is done according to the given
76.Fa base ,
77which must be between 2 and 36 inclusive,
78or be the special value 0.
79.Pp
80The string may begin with an arbitrary amount of white space
81(as determined by
82.Xr isspace 3 )
83followed by a single optional
84.Ql +
85or
86.Ql -
87sign.
88If
89.Fa base
90is zero or 16,
91the string may then include a
92.Ql 0x
93prefix,
94and the number will be read in base 16; otherwise, a zero
95.Fa base
96is taken as 10 (decimal) unless the next character is
97.Ql 0 ,
98in which case it is taken as 8 (octal).
99.Pp
100The remainder of the string is converted to a
101.Em long
102value in the obvious manner,
103stopping at the first character which is not a valid digit
104in the given base.
105(In bases above 10, the letter
106.Ql A
107in either upper or lower case
108represents 10,
109.Ql B
110represents 11, and so forth, with
111.Ql Z
112representing 35.)
113.Pp
114If
115.Fa endptr
116is non nil,
117.Fn strtol
118stores the address of the first invalid character in
119.Fa *endptr .
120If there were no digits at all, however,
121.Fn strtol
122stores the original value of
123.Fa nptr
124in
125.Fa *endptr .
126(Thus, if
127.Fa *nptr
128is not
129.Ql \e0
130but
131.Fa **endptr
132is
133.Ql \e0
134on return, the entire string was valid.)
135.Sh RETURN VALUES
136The
137.Fn strtol
138function
139returns the result of the conversion,
140unless the value would underflow or overflow.
141If an underflow occurs,
142.Fn strtol
143returns
144.Dv LONG_MIN .
145If an overflow occurs,
146.Fn strtol
147returns
148.Dv LONG_MAX .
149In both cases,
150.Va errno
151is set to
152.Er ERANGE .
153.Sh ERRORS
154.Bl -tag -width [ERANGE]
155.It Bq Er ERANGE
156The given string was out of range; the value converted has been clamped.
157.El
158.Sh SEE ALSO
159.Xr atof 3 ,
160.Xr atoi 3 ,
161.Xr atol 3 ,
162.Xr strtod 3 ,
163.Xr strtoul 3
164.Sh STANDARDS
165The
166.Fn strtol
167function
168conforms to
169.St -ansiC .
170.Sh BUGS
171Ignores the current locale.
172