STRTONUM(3) | Library Functions Manual | STRTONUM(3) |
strtonum
—
#include
<stdlib.h>
long long
strtonum
(const char *nptr,
long long minval, long long
maxval, const char **errstr);
strtonum
() function converts the string in
nptr to a long long
value.
The string may begin with an arbitrary amount of whitespace (as
determined by isspace(3))
followed by a single optional ‘+
’ or
‘-
’ sign.
The remainder of the string is converted to a
long long
value according to base 10.
The value obtained is then checked against the provided
minval and maxval bounds. If
errstr is non-null, strtonum
()
stores an error string in *errstr indicating the
failure.
strtonum
() function returns the result of the
conversion, unless the value would exceed the provided bounds or is invalid.
On error, 0 is returned, errno is set, and
errstr will point to an error message.
*errstr will be set to NULL
on
success; this fact can be used to differentiate a successful return of 0 from
an error.
strtonum
() correctly is meant to be simpler than
the alternative functions.
int iterations; const char *errstr; iterations = strtonum(optarg, 1, 64, &errstr); if (errstr) errx(1, "number of iterations is %s: %s", errstr, optarg);
The above example will guarantee that the value of iterations is between 1 and 64 (inclusive).
EINVAL
]ERANGE
]If an error occurs, errstr will be set to one of the following strings:
strtonum
() is an OpenBSD
extension.
strtonum
() function first appeared in
OpenBSD 3.6. strtonum
() was
redesigned in NetBSD 8 as
strtoi
(3) and
strtou
(3). For compatibility
reasons it's available since NetBSD 8 in the
_OPENBSD_SOURCE namespace.
strtonum
() function was designed to facilitate safe,
robust programming and overcome the shortcomings of the
atoi(3) and
strtol(3) family of interfaces,
however there are problems with the strtonum
() API:
strtonum
()
NetBSD provides
strtou
(3) and
strtoi
(3).
January 18, 2015 | NetBSD 9.2 |