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Top Forums Programming A question about printing error message with perror Post 302344249 by dariyoosh on Saturday 15th of August 2009 11:38:06 AM
Old 08-15-2009
Quote:
Originally Posted by pludi
Did you read up on what perror() does?
Since neither you nor any other function set errno, it's probably defaulted to zero, which means success.

If you want to output any error messages that stem from logical errors, I'd suggest writing them to stderr via fprintf.

Dear pludi


Thank you very much for your help. Your solution solved my problem.

Code:
if (argc != 3)
{
    fprintf(stderr, "use: ./myProgram <source file> <target file>\n");
    return 1;
}

And it prints only the error message.


Thanks a lot for your help.


Kind Regards,
Smilie
 

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PERROR(3)						     Library Functions Manual							 PERROR(3)

NAME
perror, strerror - system error messages SYNOPSIS
perror(s) char *s; #include <string.h> char * strerror(errnum) int errnum; DESCRIPTION
The strerror() and perror() functions look up the error message string corresponding to an error number. The strerror() function accepts an error number argument errnum and returns a pointer to the corresponding message string. The perror() function finds the error message corresponding to the current value of the global variable errno (intro(2)) and writes it, followed by a newline, to the standard error file descriptor. If the argument string is non-NULL, it is prepended to the message string and separated from it by a colon and space (`: '). If string is NULL, only the error message string is printed. If errnum is not a recognized error number, the error message string will contain ``Unknown error: '' followed by the error number in deci- mal. The error messages are stored in a data file now rather than an in memory array. See syserror(5). SEE ALSO
mkerrlst(1), intro(2), psignal(3), strerror(3), syserror(3), syserror(5) BUGS
The strerror() function returns its result in a static buffer which may be overwritten by subsequent calls. The array sys_errlist[] and the global sys_nerr are obsolete and should not be used. They have, for the time being, been placed in an object library liberrlst.a. 4th Berkeley Distribution March 21, 1996 PERROR(3)
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