NAME
strtol, strtoll,
strtoimax, 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>
#include <stdlib.h>
#include <limits.h>
quad_t
strtoq(const
char *nptr, char
**endptr, int
base);
DESCRIPTION
Thestrtol()
function converts the string in nptr to a
long value. The
strtoll()
function converts the string in nptr to a
long long 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
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 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()
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(),
strtoll(), strtoimax() 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 |
strtoll() |
LLONG_MIN |
LLONG_MAX |
strtoimax() |
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)
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.