ATOI(3) Linux Programmer's Manual ATOI(3)
atoi, atol, atoll - convert a string to an integer
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)):
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 ||
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99
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.
The converted value.
Multithreading (see pthreads(7))
The atoi(), atol(), and atoll() functions are thread-safe with excep-
tions. These functions can be safely used in multithreaded applica-
tions, as long as setlocale(3) is not called to change the locale dur-
ing their execution.
SVr4, POSIX.1-2001, 4.3BSD, C99. C89 and POSIX.1-1996 include the
functions atoi() and atol() only.
Linux libc provided atoq() as an obsolete name for atoll(); atoq() is
not provided by glibc.
atof(3), strtod(3), strtol(3), strtoul(3)
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GNU 2014-08-19 ATOI(3)