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perror() Print Error Message
#include <stdlib.h> Required for declarations only
void perror(string);
char *string; User-supplied message
int errno; Error number
int sys_nerr; Number of system messages
char sys_errlist[sys_nerr]; Array of error messages
perror() prints an error message to 'stderr'. In order, perror()
prints:
the user-supplied string argument
a colon
system error message for last library call producing an error
a new-line character
System error messages are accessed through an array of messages,
ordered by 'errno', called 'sys_errlist'. The error number generated
by the most recent system call is stored in the external variable,
'errno' (which should be declared at the external level); 'errno'
thus reflects the most recent error generated by a system library
call in the current program. perror uses errno as an index to
sys_errlist to print the appropriate error message. 'sys_nerr'
contains the maximum number of elements in 'sys_errlist'.
Returns: There is no return value.
Notes: Call perror() immediately after the system call returns
with an error. Otherwise, the error number in 'errno' may
be overwritten by an error generated by a subsequent
system call.
-------------------------------- Example ---------------------------------
#include <fcntl.h> /* constants defined */
#include <sys\types.h>
#include <sys\stat.h> /* constants defined */
#include <io.h> /* for open */
#include <stdlib.h>
int fhndl;
main()
{
if ((fhndl = open("inp.dat",O_RDONLY)) == -1)
perror("unable to open file");
}
See Also:
clearerr()
ferror()
strerror()
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