C Error Message
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C Print Error Message Errno
Selected Reading Developer's Best Practices Questions and Answers Effective Resume Writing HR Interview Questions Computer Glossary Who is Who C - Error Handling Advertisements Previous Page Next Page As such, C programming does not provide direct support for error handling but being a system programming language, it provides you access at lower level in the form of return values. Most of the C or even Unix function calls return -1 or NULL in case of any c exit with error message error and set an error code errno. It is set as a global variable and indicates an error occurred during any function call. You can find various error codes defined in
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Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Printing error messages up vote 3 down vote favorite https://www.tutorialspoint.com/cprogramming/c_error_handling.htm 2 I am just wondering what is the best way to make custom print error functions. For example I have some #defines like this in header file: #define SOCKET_ERR 0 #define BIND_ERR 1 #define LISTEN_ERR 2 etc Then maybe using this like this: if(/*something has gone wrong with socket*/) { print_error(SOCKET_ERR); } print_error(int error) { if(error == 0) { printf("Socket failure\n"); } } However, I don't think this http://stackoverflow.com/questions/1679117/printing-error-messages perfect and want to do something much better. Maybe something a little bit more professional and maybe more scalable. Many thanks for any advice, c share|improve this question asked Nov 5 '09 at 8:30 ant2009 55786241392 1 Use 'fprintf(stderr, ...)' to report errors (or, at least, normally write to 'stderr' rather than 'stdout' - or write to a log file, or both log file and stderr). –Jonathan Leffler Nov 5 '09 at 8:51 add a comment| 3 Answers 3 active oldest votes up vote 3 down vote accepted You might consider using variadic functions for error reporting, they become so much more versatile. For instance #include
optionally preceding it with the custom message specified in str. errno is an http://www.cplusplus.com/reference/cstdio/perror/ integral variable whose value describes the error condition or diagnostic https://www.thinkage.ca/english/gcos/expl/c/lib/perror.html information produced by a call to a library function (any function of the C standard library may set a value for errno, even if not explicitly specified in this reference, and even if no error happened), see errno for more error message info. The error message produced by perror is platform-depend. If the parameter str is not a null pointer, str is printed followed by a colon (:) and a space. Then, whether str was a null pointer or not, the generated error description is printed followed by a newline character ('\n'). perror c print error should be called right after the error was produced, otherwise it can be overwritten by calls to other functions. Parameters. str C string containing a custom message to be printed before the error message itself. If it is a null pointer, no preceding custom message is printed, but the error message is still printed. By convention, the name of the application itself is generally used as parameter. Return Value none Example 1
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/* perror example */ #include
followed by a colon and a blank, followed by the error message generated by "strerror". The most helpful sort of string would be the name of the program or some similar identifier. Description: "perror" prints out an error message based on the current value of the external variable "errno". The value of "errno" is set by C library functions when error conditions are encountered. Thus the message printed by "perror" reflects the last error encountered during a call to a library function. The function "strerror" obtains the text of the appropriate error message. See Also: expl c lib errno expl c lib strerror Copyright © 1996, Thinkage Ltd.