GNU/Linux man pages
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Syntaxe et mise en oeuvre :
GNU/Linux |
CentOS 5.4 |
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atoi(3p) |
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atoi − convert a string to an integer
#include <stdlib.h>
int atoi(const char *str);
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() , the Base Definitions volume of IEEE Std 1003.1-2001, <stdlib.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard 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 .
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atoi(3p) | |