NAME
strtoul, strtoull,
strtoumax, strtouq —
convert a string to an
unsigned long, unsigned long
long, uintmax_t, or
u_quad_t integer
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include
<stdlib.h>
unsigned long
strtoul(const char *restrict
str, char **restrict endptr, int
base);
unsigned long long
strtoull(const char *restrict
str, char **restrict endptr, int
base);
#include
<inttypes.h>
uintmax_t
strtoumax(const char *restrict
str, char **restrict endptr, int
base);
#include
<sys/types.h>
#include <stdlib.h>
#include <limits.h>
u_quad_t
strtouq(const char *str,
char **endptr, int base);
DESCRIPTION
The
strtoul()
function converts the string in str to an
unsigned long value. The
strtoull()
function converts the string in str to an
unsigned long long value. The
strtoumax()
function converts the string in str to an
uintmax_t value. The
strtouq()
function converts the string in str to a
u_quad_t value. The conversion is done according to
the given base, which must be between 2 and 36
inclusive, or be the special value 0.
The string may begin with an arbitrary amount of white space (as
determined by isspace(3)) followed by a single optional
‘+’ or
‘-’ sign. If
base is zero or 16, the string may then include a
“0x” prefix, and the number will be
read in base 16; otherwise, a zero base is taken as 10
(decimal) unless the next character is
‘0’, in which case it is taken as 8
(octal).
The remainder of the string is converted to an
unsigned long value in the obvious manner, stopping at
the end of the string or at the first character that does not produce a
valid digit in the given base. (In bases above 10, the letter
‘A’ in either upper or lower case
represents 10, ‘B’ represents 11, and
so forth, with ‘Z’ representing
35.)
If endptr is not
NULL,
strtoul()
stores the address of the first invalid character in
*endptr. If there were no digits at all, however,
strtoul() stores the original value of
str in *endptr. (Thus, if
*str is not ‘\0’
but **endptr is
‘\0’ on return, the entire string was
valid.)
RETURN VALUES
The strtoul(),
strtoull(), strtoumax() and
strtouq() functions return either the result of the
conversion or, if there was a leading minus sign, the negation of the result
of the conversion, unless the original (non-negated) value would overflow;
in the latter case, strtoul() returns
ULONG_MAX, strtoull()
returns ULLONG_MAX,
strtoumax() returns
UINTMAX_MAX, and strtouq()
returns ULLONG_MAX. In all cases,
errno is set to ERANGE. If no
conversion could be performed, 0 is returned and the global variable
errno is set to EINVAL (the
last feature is not portable across all platforms).
ERRORS
- [
EINVAL] - The value of base is not supported or no conversion could be performed (the last feature is not portable across all platforms).
- [
ERANGE] - The given string was out of range; the value converted has been clamped.
LEGACY SYNOPSIS
#include
<stdlib.h> #include
<limits.h>
<limits.h>
is necessary for the
strtoul()
and
strtoull()
functions.
SEE ALSO
STANDARDS
The strtoul() function conforms to
ISO/IEC 9899:1990 (“ISO C90”).
The strtoull() and
strtoumax() functions conform to
ISO/IEC 9899:1999 (“ISO C99”).
The BSD strtouq() function
is deprecated.