strtoimax(3)
- NetBSD Manual Pages
STRTOL(3) NetBSD Library Functions Manual STRTOL(3)
NAME
strtol, strtoll, strtoimax, strtoq -- convert string value to a long,
long long, intmax_t or quad_t integer
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <stdlib.h>
#include <limits.h>
long int
strtol(const char * restrict nptr, char ** restrict endptr, int base);
long long int
strtoll(const char * restrict nptr, char ** restrict endptr, int base);
#include <inttypes.h>
intmax_t
strtoimax(const char * restrict nptr, char ** restrict endptr, int base);
#include <sys/types.h>
#include <stdlib.h>
#include <limits.h>
quad_t
strtoq(const char * restrict nptr, char ** restrict endptr, int base);
DESCRIPTION
The strtol() function converts the string in nptr to a long int value.
The strtoll() function converts the string in nptr to a long long int
value. The strtoimax() function converts the string in nptr to an
intmax_t value. The strtoq() function converts the string in nptr to a
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 deter-
mined 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 a long 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' represent-
ing 35.)
If endptr is non nil, strtol() stores the address of the first invalid
character in *endptr. If there were no digits at all, however, strtol()
stores the original value of nptr in *endptr. (Thus, if *nptr is not
`\0' but **endptr is `\0' on return, the entire string was valid.)
RETURN VALUES
The strtol() function returns the result of the conversion, unless the
value would underflow or overflow. If an underflow occurs, strtol()
returns LONG_MIN, strtoll() returns LLONG_MIN, and strtoimax() returns
INTMAX_MIN. If an overflow occurs, strtol() returns LONG_MAX, strtoll()
returns LLONG_MAX, and strtoimax() returns INTMAX_MAX. In these cases,
errno is set to ERANGE.
EXAMPLES
Ensuring that a string is a valid number (i.e., in range and containing
no trailing characters) requires clearing errno beforehand explicitly
since errno is not changed on a successful call to strtol(), and the
return value of strtol() cannot be used unambiguously to signal an error:
char *ep;
long lval;
...
errno = 0;
lval = strtol(buf, &ep, 10);
if (buf[0] == '\0' || *ep != '\0')
goto not_a_number;
if (errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN))
goto out_of_range;
This example will accept ``12'' but not ``12foo'' or ``12\n''. If trail-
ing whitespace is acceptable, further checks must be done on *ep; alter-
nately, use sscanf(3).
If strtol() is being used instead of atoi(3), error checking is further
complicated because the desired return value is an int rather than a
long; however, on some architectures integers and long integers are the
same size. Thus the following is necessary:
char *ep;
int ival;
long lval;
...
errno = 0;
lval = strtol(buf, &ep, 10);
if (buf[0] == '\0' || *ep != '\0')
goto not_a_number;
if ((errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN)) ||
(lval > INT_MAX || lval < INT_MIN))
goto out_of_range;
ival = lval;
ERRORS
[ERANGE] The given string was out of range; the value converted
has been clamped.
SEE ALSO
atof(3), atoi(3), atol(3), atoll(3), strtod(3), strtoul(3), strtoull(3),
strtoumax(3)
STANDARDS
The strtol() function conforms to ANSI X3.159-1989 (``ANSI C89''). The
strtoll() and strtoimax() functions conform to ISO/IEC 9899:1999
(``ISO C99'').
BUGS
Ignores the current locale.
NetBSD 4.0 August 11, 2002 NetBSD 4.0
Powered by man-cgi (2024-03-20).
Maintained for NetBSD
by Kimmo Suominen.
Based on man-cgi by Panagiotis Christias.