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Name

atoi, atol, atoll - convert a string to an integer

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():

_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99

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.

Attributes

Multithreading (see pthreads(7) )

The atoi(), atol(), and atoll() functions are thread-safe with exceptions. These functions can be safely used in multithreaded applications, as long as setlocale(3) is not called to change the locale during their execution.

Conforming to

SVr4, POSIX.1-2001, 4.3BSD, C99. C89 and POSIX.1-1996 include the functions atoi() and atol() only.

Notes

Linux libc provided atoq() as an obsolete name for atoll(); atoq() is not provided by glibc.

See Also

atof(3) , strtod(3) , strtol(3) , strtoul(3)

Colophon

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