Error Code C Programming
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Error Handling In C++
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 error and set an error code errno. It is set as a global variable and indicates an error occurred during any function call. error handling in c pdf You can find various error codes defined in
known as exception handling). By convention, the programmer is expected to prevent errors from occurring in the first place, and test return values from functions. For example, -1
C Throw Error
and NULL are used in several functions such as socket() (Unix socket programming)
C Exit With Error Message
or malloc() respectively to indicate problems that the programmer should be aware about. In a worst case scenario try catch in c where there is an unavoidable error and no way to recover from it, a C programmer usually tries to log the error and "gracefully" terminate the program. There is an external https://www.tutorialspoint.com/cprogramming/c_error_handling.htm variable called "errno", accessible by the programs after including
Programming Boards C Programming returning an error code from a function that has a pointer return type Getting started with C or C++ | C Tutorial | C++ Tutorial http://cboard.cprogramming.com/c-programming/147824-returning-error-code-function-has-pointer-return-type.html | C and C++ FAQ | Get a compiler | Fixes for common problems Thread: returning an error code from a function that has a pointer return type Thread Tools Show Printable Version Email this Page… http://www.thegeekstuff.com/2010/10/linux-error-codes Subscribe to this Thread… Display Linear Mode Switch to Hybrid Mode Switch to Threaded Mode 04-18-2012 #1 tieske View Profile View Forum Posts Registered User Join Date Apr 2012 Posts 7 returning an error code error handling from a function that has a pointer return type I have tried several google searches, but probably use the wrong keywords to find this. I have a function that returns a pointer type, now if the function detects an error condition I would like the caller to be able to check the returned type for a specific error condition instead of only being able to return NULL as a failure error handling in indication. I understand that pointers are numeric values int/long etc. but what's the best approach to do this and make sure I don't define a possible proper pointer value as an error code? example of what I would like to achieve (not actual code used); Code: #define BADPARAMETER -1 void* myfunc(int myparam) { if (myparam < 0) return BADPARAMETER; .... } caller code Code: result = myfunc(somevalue); if (result == BADPARAMETER) { .... handle returned error } Probably has been done before, so any pointers to a solution are appreciated. Thijs 04-18-2012 #2 laserlight View Profile View Forum Posts Visit Homepage C++ Witch Join Date Oct 2003 Location Singapore Posts 25,447 One approach: Code: void* myfunc(int myparam, int* err_code) { if (myparam < 0) { if (err_code) { *err_code = BADPARAMETER; } return NULL; } /* .... */ } So, if the caller wants more information, the caller provides the address of an int to which the error code is saved. Otherwise, the only indication of an error is the null pointer that is returned. Originally Posted by Bjarne Stroustrup (2000-10-14) I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of line
In C programming language, there is no direct support for error handling. You have to detect the failure and handle the error. In C programming language, return values represents success or failure. Inside a C program, when a function fails, you should handle the errors accordingly, or at least record the errors in a log file. When you are running some program on Linux environment, you might notice that it gives some error number. For example, "Error no is : 17", which doesn't really say much. You really need to know what error number 17 means. This article shows all available error numbers along with it descriptions. This article might be a handy reference for you, when you encounter an error number and you would like to know what it means. In C programming language, there is an external variable called "errno". From this errno variable you can use some error handling functions to find out the error description and handle it appropriately. You have to include errno.h header file to use external variable errno. perror function prints error description in standard error. The strerror function returns a string describing the error code passed in the argument errnum. The following C code snippet tries to open a file through open system call. There are two flags in the open call. O_CREAT flag is to create a file, if the file does not exist. O_EXCL flag is used with O_CREAT, if the file is already exist open call will fail with the proper error number. $ cat fileopen.c #include