преобразовать строку в целое число (convert a string to an integer)
Имя (Name)
atoi, atol, atoll - convert a string to an integer
Синопсис (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
Описание (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.
Возвращаемое значение (Return value)
The converted value or 0 on error.
Атрибуты (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 │
└───────────────────────────────┴───────────────┴────────────────┘
Стандарты (Conforming to)
POSIX.1-2001, POSIX.1-2008, C99, SVr4, 4.3BSD. C89 and
POSIX.1-1996 include the functions atoi() and atol() only.
Примечание (Note)
POSIX.1 leaves the return value of atoi() on error unspecified.
On glibc, musl libc, and uClibc, 0 is returned on error.
Ошибки (баги) (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.
Смотри также (See also)
atof(3), strtod(3), strtol(3), strtoul(3)
