C Program Error Codes
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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
C Error Codes In Linux
handle the errors accordingly, or at least record the errors in a log file. When you corsa c error codes are running some program on Linux environment, you might notice that it gives some error number. For example, "Error no is : 17", which vectra c error codes 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
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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
Turbo C Program Codes
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
statement 2.2 Using = instead of == 2.3 scanf() errors 2.3.1 Forgetting to put an ampersand (&) on arguments 2.3.2 Using the linux kernel error codes wrong format for operand 2.4 Size of arrays 2.5 Integer division 2.6
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Loop errors 2.7 Not using prototypes 2.8 Not initializing pointers 3. String Errors 3.1 Confusing character and linux error codes 127 string constants 3.2 Comparing strings with == 3.3 Not null terminating strings 3.4 Not leaving room for the null terminator 4. Input/Output Errors 4.1 Using fgetc(), etc. incorrectly 4.2 http://www.thegeekstuff.com/2010/10/linux-error-codes/ Using feof() incorrectly 4.3 Leaving characters in the input buffer 4.4 Using the gets() function 5. Acknowlegements 1. Introduction This document lists the common C programming errors that the author sees time and time again. Solutions to the errors are also presented. Another great resource is the C FAQ. Gimpel Software also has a list of hard to detect http://www.drpaulcarter.com/cs/common-c-errors.php C/C++ bugs that might be useful. There is also a French translation of this page (thanks to Amine Brikci-Nigassa!). 2. Beginner Errors These are errors that beginning C students often make. However, the professionals still sometimes make them too! 2.1 Forgetting to put a break in a switch statement Remember that C does not break out of a switch statement if a case is encountered. For example: int x = 2; switch(x) { case 2: printf("Two\n"); case 3: printf("Three\n"); } prints out: Two Three Put a break to break out of the switch: int x = 2; switch(x) { case 2: printf("Two\n"); break; case 3: printf("Three\n"); break; /* not necessary, but good if additional cases are added later */ } 2.2 Using = instead of == C's = operator is used exclusively for assignment and returns the value assigned. The == operator is used exclusively for comparison and returns an integer value (0 for false, not 0 for true). Because of these return values, the C compiler often does not flag an error
Practice Problems Quizzes Resources Source Code Source Code Snippets C and C++ Tips Finding a Job References Function Reference Syntax Reference Programming FAQ Getting Help Message Board Email http://www.cprogramming.com/tutorial/common.html About Us 8 Common Programming Mistakes By Alex Allain Learning to program http://stackoverflow.com/questions/385975/error-handling-in-c-code can be tough--just ask anyone who's done it! Fortunately, a lot of problems happen over and over again--I've put together 8 of the most common problems that you'll run into as a new programmer. 1. Undeclared Variables int main() { cin>>x; cout< here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community 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 Error handling in C code up vote 102 down vote favorite 59 What do you consider "best practice" when it comes to error handling errors in a consistent way in a C library. There are two ways I've been thinking of: Always return error code. A typical function would look like this: MYAPI_ERROR getObjectSize(MYAPIHandle h, int* returnedSize); The always provide an error pointer approach: int getObjectSize(MYAPIHandle h, MYAPI_ERROR* returnedError); When using the first approach it's possible to write code like this where the error handling check is directly placed on the function call: int size; if(getObjectSize(h, &size) != MYAPI_SUCCESS) { // Error handling } Which looks better than the error handling code here. MYAPIError error; int size; size = getObjectSize(h, &error); if(error != MYAPI_SUCCESS) { // Error handling } However, I think using the return value for returning data makes the code more readable, It's obvious that something was written to the size variable in the second example. Do you have any ideas on why I should prefer any of those approaches or perhaps mix them or use something else? I'm not a fan of global error states since it tends to make multi threaded use of the library way more painful. EDIT: C++ specific ideas on this would also be interesting to hear about as long as they are not involving exceptions since it's not an option for me at the moment... c error-handling share|improve this question edited Nov 6 '13 at 19:09 ubershmekel 3,61513144 asked Dec 22 '08 at 10:46 Laserallan 6,70172956 add a comment| 17 Answers 17 active oldest votes up vote 49 down vote accepted I like the error as return-value way. If you're designing the api and you want to make use of your library as painless as possible think about these additions: store all possible error-states in one typedef'ed enum and use it in your lib. Don't just return ints or even worse, mix ints or different enumerations with return-codes. provide a function that converts errors into something human readable. Can be simple. Just error-enum in, const char* out. I know this idea makes multithreaded use a bit difficult, b