|
PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
ATOI(3P) POSIX Programmer's Manual ATOI(3P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
atoi — convert a string to an integer
#include <stdlib.h>
int atoi(const char *str);
The functionality described on this reference page is aligned with
the ISO C standard. Any conflict between the requirements described
here and the ISO C standard is unintentional. This volume of
POSIX.1‐2008 defers to the ISO C standard.
The call atoi(str) shall be equivalent to:
(int) strtol(str, (char **)NULL, 10)
except that the handling of errors may differ. If the value cannot be
represented, the behavior is undefined.
The atoi() function shall return the converted value if the value can
be represented.
No errors are defined.
The following sections are informative.
Converting an Argument
The following example checks for proper usage of the program. If
there is an argument and the decimal conversion of this argument
(obtained using atoi()) is greater than 0, then the program has a
valid number of minutes to wait for an event.
#include <stdlib.h>
#include <stdio.h>
...
int minutes_to_event;
...
if (argc < 2 || ((minutes_to_event = atoi (argv[1]))) <= 0) {
fprintf(stderr, "Usage: %s minutes\n", argv[0]); exit(1);
}
...
The atoi() function is subsumed by strtol() but is retained because
it is used extensively in existing code. If the number is not known
to be in range, strtol() should be used because atoi() is not
required to perform any error checking.
None.
None.
strtol(3p)
The Base Definitions volume of POSIX.1‐2008, stdlib.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 ATOI(3P)
Pages that refer to this page: stdlib.h(0p)