ATOI(3) - man page online | library functions

Convert a string to an integer.

ATOI(3)                             Linux Programmer's Manual                             ATOI(3)

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 For an explanation of the terms used in this section, see attributes(7). ┌────────────────────────┬───────────────┬────────────────┐ │Interface │ Attribute │ Value │ ├────────────────────────┼───────────────┼────────────────┤ │atoi(), atol(), atoll() │ Thread safety │ MT-Safe locale │ └────────────────────────┴───────────────┴────────────────┘
CONFORMING TO POSIX.1-2001, POSIX.1-2008, C99, SVr4, 4.3BSD. 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 This page is part of release 4.04 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at
GNU 2015-08-08 ATOI(3)
This manual Reference Other manuals
atoi(3) referred by a2x(3bobcat) | atof(3) | field_validation(3form) | strtod(3) | strtol(3) | strtonum(3) | strtoul(3)
refer to atof(3) | attributes(7) | feature_test_macros(7) | strtod(3) | strtol(3) | strtoul(3)