xref: /freebsd/lib/libc/stdlib/strtol.3 (revision 8fa113e5fc65fe6abc757f0089f477a87ee4d185)
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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 , strtoll , strtoimax , strtoq
44.Nd "convert a string value to a long, long long, intmax_t or quad_t integer"
45.Sh LIBRARY
46.Lb libc
47.Sh SYNOPSIS
48.In stdlib.h
49.In limits.h
50.Ft long
51.Fn strtol "const char *nptr" "char **endptr" "int base"
52.Ft long long
53.Fn strtoll "const char *nptr" "char **endptr" "int base"
54.In inttypes.h
55.Ft intmax_t
56.Fn strtoimax "const char *nptr" "char **endptr" "int base"
57.In sys/types.h
58.In stdlib.h
59.In limits.h
60.Ft quad_t
61.Fn strtoq "const char *nptr" "char **endptr" "int base"
62.Sh DESCRIPTION
63The
64.Fn strtol
65function
66converts the string in
67.Fa nptr
68to a
69.Em long
70value.
71The
72.Fn strtoll
73function
74converts the string in
75.Fa nptr
76to a
77.Em long long
78value.
79The
80.Fn strtoimax
81function
82converts the string in
83.Fa nptr
84to an
85.Em intmax_t
86value.
87The
88.Fn strtoq
89function
90converts the string in
91.Fa nptr
92to a
93.Em quad_t
94value.
95The conversion is done according to the given
96.Fa base ,
97which must be between 2 and 36 inclusive,
98or be the special value 0.
99.Pp
100The string may begin with an arbitrary amount of white space
101(as determined by
102.Xr isspace 3 )
103followed by a single optional
104.Ql +
105or
106.Ql -
107sign.
108If
109.Fa base
110is zero or 16,
111the string may then include a
112.Ql 0x
113prefix,
114and the number will be read in base 16; otherwise, a zero
115.Fa base
116is taken as 10 (decimal) unless the next character is
117.Ql 0 ,
118in which case it is taken as 8 (octal).
119.Pp
120The remainder of the string is converted to a
121.Em long ,
122.Em long long ,
123.Em intmax_t
124or
125.Em quad_t
126value in the obvious manner,
127stopping at the first character which is not a valid digit
128in the given base.
129(In bases above 10, the letter
130.Ql A
131in either upper or lower case
132represents 10,
133.Ql B
134represents 11, and so forth, with
135.Ql Z
136representing 35.)
137.Pp
138If
139.Fa endptr
140is non nil,
141.Fn strtol
142stores the address of the first invalid character in
143.Fa *endptr .
144If there were no digits at all, however,
145.Fn strtol
146stores the original value of
147.Fa nptr
148in
149.Fa *endptr .
150(Thus, if
151.Fa *nptr
152is not
153.Ql \e0
154but
155.Fa **endptr
156is
157.Ql \e0
158on return, the entire string was valid.)
159.Sh RETURN VALUES
160The
161.Fn strtol ,
162.Fn strtoll ,
163.Fn strtoimax
164or
165.Fn strtoq
166function
167returns the result of the conversion,
168unless the value would underflow or overflow.
169If no conversion could be performed, 0 is returned and
170the global variable
171.Va errno
172is set to
173.Er EINVAL .
174If an overflow or underflow occurs,
175.Va errno
176is set to
177.Er ERANGE
178and the function return value is clamped according
179to the following table.
180.Bl -column -offset indent ".Fn strtoimax" ".Sy overflow" ".Sy underflow"
181.It Sy Function Ta Sy overflow Ta Sy underflow
182.It Fn strtol Ta Dv LONG_MIN Ta Dv LONG_MAX
183.It Fn strtoll Ta Dv LLONG_MIN Ta Dv LLONG_MAX
184.It Fn strtoimax Ta Dv INTMAX_MIN Ta Dv INTMAX_MAX
185.It Fn strtoq Ta Dv LLONG_MIN Ta Dv LLONG_MAX
186.El
187.Sh ERRORS
188.Bl -tag -width Er
189.It Bq Er EINVAL
190The value of
191.Fa base
192is not supported or
193no conversion could be performed.
194.It Bq Er ERANGE
195The given string was out of range; the value converted has been clamped.
196.El
197.Sh SEE ALSO
198.Xr atof 3 ,
199.Xr atoi 3 ,
200.Xr atol 3 ,
201.Xr strtod 3 ,
202.Xr strtoul 3
203.Sh STANDARDS
204The
205.Fn strtol
206function
207conforms to
208.St -isoC .
209The
210.Fn strtoll
211and
212.Fn strtoimax
213functions
214conform to
215.St -isoC-99 .
216The
217.Bx
218.Fn strtoq
219function is deprecated.
220