Manpages - strtonum.3bsd
(See
for include usage.)
The
function converts the string in
to a
value.
The string may begin with an arbitrary amount of whitespace (as determined by
followed by a single optional
or
sign.
The remainder of the string is converted to a
value according to base 10.
The value obtained is then checked against the provided
and
bounds. If
is non-null,
stores an error string in
indicating the failure.
The
function returns the result of the conversion, unless the value would exceed the provided bounds or is invalid. On error, 0 is returned,
is set, and
will point to an error message. On success,
will be set to
this fact can be used to differentiate a successful return of 0 from an error.
Using
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).
The given string did not consist solely of digit characters; or
was larger than
The given string was out of range.
If an error occurs,
will be set to one of the following strings:
The result was larger than the provided maximum value.
The result was smaller than the provided minimum value.
The string did not consist solely of digit characters.
is an
extension.
The
function first appeared in
was redesigned in
as
and
The
function was designed to facilitate safe, robust programming and overcome the shortcomings of the
and
family of interfaces, however there are problems with the
API:
will return 0 on failure; 0 might not be in range, so that necessitates an error check even if you want to avoid it
does not differentiate ’illegal’ returns, so we can’t tell the difference between partial and no conversions
returns english strings
can’t set the base, or find where the conversion ended
hardcodes long long integer type
To overcome the shortcomings of
provides
and