NAME
strtol, strtol_l,
strtoll, strtoll_l,
strtoimax, strtoimax_l,
strtoq —
convert a string value to a
long, long long,
intmax_t or quad_t
integer
LIBRARY
library “libc”
SYNOPSIS
#include
<stdlib.h>
#include <limits.h>
long
strtol(const
char * restrict nptr,
char ** restrict endptr,
int base);
long long
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>
quad_t
strtoq(const
char *nptr, char
**endptr, int
base);
#include
<xlocale.h>
long
strtol_l(const
char * restrict nptr,
char ** restrict endptr,
int base,
locale_t locale);
long long
strtoll_l(const
char * restrict nptr,
char ** restrict endptr,
int base,
locale_t locale);
intmax_t
strtoimax_l(const
char * restrict nptr,
char ** restrict endptr,
int base,
locale_t locale);
DESCRIPTION
Thestrtol()
and strtol_l() functions convert the string in
nptr to a long value. The
strtoll()
and strtoll_l() functions convert the string in
nptr to a long long value. The
strtoimax()
and strtoimax_l() functions convert 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
determined by
isspace(3) or
isspace_l(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, long long,
intmax_t or quad_t 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,
strtol()
and strtol_l() store the address of the first
invalid character in *endptr. If there were no digits
at all, however, strtol() and
strtol_l() store the original value of
nptr in *endptr. (Thus, if
*nptr is not
‘\0’ but
**endptr is ‘\0’
on return, the entire string was valid.)
The
strtol_l(),
strtoll_l(),
and
strtoimax_l()
functions take an explicit locale argument, whereas
the strtol(), strtoll(),
strtoimax(), and
strtoq()
functions use the current global or per-thread locale.
RETURN VALUES
The strtol(),
strtol_l(), strtoll(),
strtoll_l(), strtoimax(),
strtoimax_l(), and strtoq()
functions return the result of the conversion, unless the value would
underflow or overflow. 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). If an overflow or underflow occurs, errno
is set to ERANGE and the function return value is
clamped according to the following table.
| Function | underflow | overflow |
strtol() |
LONG_MIN |
LONG_MAX |
strtol_l() |
LONG_MIN |
LONG_MAX |
strtoll() |
LLONG_MIN |
LLONG_MAX |
strtoll_l() |
LLONG_MIN |
LLONG_MAX |
strtoimax() |
INTMAX_MIN |
INTMAX_MAX |
strtoimax_l() |
INTMAX_MIN |
INTMAX_MAX |
strtoq() |
LLONG_MIN |
LLONG_MAX |
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.
SEE ALSO
atof(3), atoi(3), atol(3), strtod(3), strtonum(3), strtoul(3), wcstol(3), xlocale(3)
STANDARDS
The strtol() function conforms to
ISO/IEC 9899:1990 (“ISO C90”).
The strtoll() and
strtoimax() functions conform to
ISO/IEC 9899:1999 (“ISO C99”).
The BSD strtoq() -function
is deprecated.