atoi
Section: C Library Functions (3)
Updated: 2023-02-05
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NAME
atoi, atol, atoll - convert a string to an integer
LIBRARY
Standard C library
(libc, -lc)
SYNOPSIS
#include <stdlib.h>
int atoi(const char *nptr);
long atol(const char *nptr);
long long atoll(const char *nptr);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
atoll():
_ISOC99_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
DESCRIPTION
The
atoi()
function converts the initial portion of the string
pointed to by nptr to
int.
The behavior is the same as
strtol(nptr, NULL, 10);
except that
atoi()
does not detect errors.
The
atol()
and
atoll()
functions behave the same as
atoi(),
except that they convert the initial portion of the
string to their return type of long or long long.
RETURN VALUE
The converted value or 0 on error.
ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).
| Interface | Attribute | Value
|
|
atoi(),
atol(),
atoll()
| Thread safety | MT-Safe locale
|
STANDARDS
POSIX.1-2001, POSIX.1-2008, C99, SVr4, 4.3BSD.
NOTES
POSIX.1 leaves the return value of
atoi()
on error unspecified.
On glibc, musl libc, and uClibc, 0 is returned on error.
BUGS
errno
is not set on error so there is no way to distinguish between 0 as an
error and as the converted value.
No checks for overflow or underflow are done.
Only base-10 input can be converted.
It is recommended to instead use the
strtol()
and
strtoul()
family of functions in new programs.
SEE ALSO
atof(3),
strtod(3),
strtol(3),
strtoul(3)
Index
- NAME
-
- LIBRARY
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ATTRIBUTES
-
- STANDARDS
-
- NOTES
-
- BUGS
-
- SEE ALSO
-
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Time: 06:20:12 GMT, April 25, 2024