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Top Forums Programming A question about printing error message with perror Post 302344227 by pludi on Saturday 15th of August 2009 08:23:41 AM
Old 08-15-2009
Did you read up on what perror() does?
Quote:
Originally Posted by man perror
The perror() function finds the error message corresponding to the current value of the global variable errno and writes it, followed by a newline, to the standard error file descriptor. If the argument s is non-NULL and does not point to the null character, this string is prepended to the message string and separated from it by a colon and space (": "); otherwise, only the error message string is printed.
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.
 

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perror(3C)						   Standard C Library Functions 						perror(3C)

NAME
perror, errno - print system error messages SYNOPSIS
#include <stdio.h> void perror(const char *s) #include <errno.h> int errno; DESCRIPTION
The perror() function produces a message on the standard error output (file descriptor 2) describing the last error encountered during a call to a system or library function. The argument string s is printed, followed by a colon and a blank, followed by the message and a NEW- LINE character. If s is a null pointer or points to a null string, the colon is not printed. The argument string should include the name of the program that incurred the error. The error number is taken from the external variable errno, which is set when errors occur but not cleared when non-erroneous calls are made. See Intro(2). In the case of multithreaded applications, the -mt option must be specified on the command line at compilation time (see threads(5)). When the -mt option is specified, errno becomes a macro that enables each thread to have its own errno. This errno macro can be used on either side of the assignment as though it were a variable. USAGE
Messages printed from this function are in the native language specified by the LC_MESSAGES locale category. See setlocale(3C). ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
Intro(2), fmtmsg(3C), gettext(3C), setlocale(3C), strerror(3C), attributes(5), standards(5), threads(5) SunOS 5.11 12 Jul 2007 perror(3C)
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