NAME¶
strtoul - convert a string to an unsigned long integer.
SYNOPSIS¶
#include <stdlib.h>
unsigned long int strtoul(const char *nptr, char **endptr,
int base)
DESCRIPTION¶
The
strtoul() function converts the string in
nptr to an unsigned
long integer value according to the given
base, which must be between 2
and 36 inclusive, or be the special value 0.
The string must 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 int value in the
obvious manner, stopping at the first character which is not 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,
strtoul() stores the original value of
nptr in
*endptr.
(Thus, if
*nptr is not `\0' but
**endptr is `\0' on return, the
entire string is valid.)
RETURN VALUE¶
The
strtoul() function returns 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 and sets the global variable
errno
to ERANGE.
ERRORS¶
- ERANGE
- The given string was out of range; the value converted has
been clamped.
SVID 3, BSD 4.3, ISO 9899
SEE ALSO¶
atof(3),
atoi(3),
atol(3),
strtod(3),
strtol(3)
BUGS¶
Ignores the current locale.