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ATOI(3P)                   POSIX Programmer's Manual                  ATOI(3P)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may dif-
       fer (consult the corresponding Linux manual page for details of Linux behavior), or the interface  may  not  be
       implemented on Linux.

NAME
       atoi - convert a string to an integer

SYNOPSIS
       #include <stdlib.h>

       int atoi(const char *str);


DESCRIPTION
       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.

RETURN VALUE
       The atoi() function shall return the converted value if the value can be represented.

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
   Converting an Argument
       The  following  example checks for proper usage of the program. If there is an argument and the decimal conver-
       sion 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);
              }
              ...

APPLICATION USAGE
       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.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       strtol(), the Base Definitions volume of IEEE Std 1003.1-2001, <stdlib.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Stan-
       dard for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group  Base
       Specifications  Issue  6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc
       and The Open Group. 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.opengroup.org/unix/online.html .



IEEE/The Open Group                  2003                             ATOI(3P)