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- Memory Management C - Command Line Arguments C Programming Resources C - Questions & Answers C - Quick Guide C - Useful Resources C - Discussion Selected Reading Developer's Best Practices Questions and Answers Effective Resume Writing HR Interview Questions error trapping java 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 error and set an error code errno. It is set as a global variable and indicates an error occurred during any error trapping definition function call. You can find various error codes defined in
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Join them; it only takes a minute: Sign up Try catch statements in C up vote 53 down vote favorite 17 I was thinking today about the try/catch blocks existent in another languages. Googled for a while this but https://www.tutorialspoint.com/cprogramming/c_error_handling.htm with no result. From what I know, there is not such a thing as try/catch in C. However, is there a way to "simulate" them? Sure, there is assert and other tricks but nothing like try/catch, that also catch the raised exception. Thank you c share|improve this question asked May 14 '12 at 15:07 Andrew 2,315103869 1 Exception-like mechanisms are not going to be generally useful without a mechanism to automatically free resources when the stack is unwound. http://stackoverflow.com/questions/10586003/try-catch-statements-in-c C++ uses RAII; Java, C#, Python, etc. use garbage collectors. (And note that garbage collectors free only memory. To automatically free other types of resources, they also add things like finalizers or context managers...) –jamesdlin May 3 '15 at 5:34 @jamesdlin, Why couldn't we do RAII with C? –Pacerier May 15 '15 at 22:45 @Pacerier RAII requires calling functions automatically when objects are destroyed (i.e., destructors). How do you propose doing that in C? –jamesdlin May 15 '15 at 23:02 add a comment| 11 Answers 11 active oldest votes up vote 47 down vote accepted C itself doesn't support exceptions but you can simulate them to a degree with setjmp and longjmp calls. static jmp_buf s_jumpBuffer; void Example() { if (setjmp(s_jumpBuffer)) { // The longjmp was executed and returned control here printf("Exception happened\n"); } else { // Normal code execution starts here Test(); } } void Test() { // Rough equivalent of `throw` longjump(s_jumpBuffer, 42); } This website has a nice tutorial on how to simulate exceptions with setjmp and longjmp http://www.di.unipi.it/~nids/docs/longjump_try_trow_catch.html share|improve this answer edited Nov 20 '14 at 0:09 SSpoke 2,81813784 answered May 14 '12 at 15:12 JaredPar 451k859201226 awesome solution! is this solution cross? It worked for me on MSVC2012 but didn't in MacOSX Clang compiler. –emanuelcds Sep 5 at 18:03 add a comment| up vote 18 down vote You use goto in C
Peter Petersen Error handling is an important issue in embedded systems, and it can account for a substantial portion of a project's code. We were faced with this issue during the design of RTFiles, http://www.on-time.com/ddj0011.htm the embedded filesystem component of On Time RTOS-32, our Win32-compatible RTOS for 32-bit x86 targets. The core filesystem is portable with a C function API to the application and a device-driver interface below it. Typically, http://rlc.vlinder.ca/blog/2010/01/error-handling-in-c/ errors can occur in device drivers and must be reported to the application with suitable return codes, so errors must travel through the complete core filesystem. The classic C approach to this problem is return codes. error trapping Each function returns a value indicating success or failure. However, with a nontrivial function call hierarchy, this approach clutters the code significantly. Every function must check the return code of every function call it makes and take care of errors. In most cases, the function will merely pass any errors back up to its caller. RTFiles has several hundred internal functions and a call hierarchy up to about 15 levels deep, so error trapping java this approach would have been a nightmare to maintain. Programming languages such as Ada or C++ address this issue with exceptions. Exceptions make it easy to separate error handling from the rest of the code. Intermediate functions can completely ignore errors occurring in functions they call, if they can't handle them anyway. Exceptions are much easier to maintain than error return codes, so we definitely wanted to use them for RTFiles. Unfortunately, we had to write RTFiles in C, and not C++ or Ada, for portability. RTFiles must support compilers without C++ support. Another issue is overhead and reliability. C++ exception handling needs a lot of run-time system support routines, which might add too much code to a small embedded system. C++ exceptions are objects dynamically allocated from the heap, but many embedded systems do not want to use any dynamic memory allocation to avoid heap fragmentation and out-of-heap-space problems. For example, what would happen if an RTFiles device driver throws a disk-write-protection exception, and the heap allocation called by throw throws an out-of-memory exception? The solution to the problem is to implement a simple exception-handling library in C with the following goals: No dynamic memory allocation. Robust (the exception handling library itself must not fail). Must support both exception-handlers and finally-handlers. R
handling in C Posted on January 16, 2010 by rlc One of the things I do as a analyst-programmer is write software - that would be the "programmer" part. I usually do that in C++ but, sometimes, when the facilities of C++ aren't available (e.g. no exception handling and no RTTI) C becomes a more obvious choice. When that happens, RTTI is not the thing I miss the most - you can get around that using magic numbers if you need to. Exceptions, on the other hand, become a very painful absence when you're used to using them. Error handling is a very important part of programming: a lot of things can go wrong when a program runs and most of those things need to be handled properly because the functionalities of your program depend on them. C++ uses exceptions for this purpose, so that if a call to foo fails, you don't have to handle that failure in the context of your call - especially if you wouldn't be able to do anything about it anyway. Thus, the following code: foo(); bar(); will call bar only if foo didn't throw any exceptions. Presumably both do something useful and neither of them return anything useful. Now, the same thing would be true in C if we did something like this: int result = foo(); if (result == 0) result = bar(); Now, both foo and bar return a result code which, in this case, is 0 if all is well. Windows programmers will be more familiar with this: HRESULT result = foo(); if (SUCCEEDED(result)) result = bar(); which amounts to the same thing. HRESULT, after all, is a 32-bit unsigned integer of which a few bits are reserved to indicate where the error originated and the other bits indicate the error. An HRESULT value of 0 means no error, so the SUCCEEDED basically checks whether the result is 0. The trouble starts when the function returned an integer already - e.g. a getFooCount function: unsigned int foo_count(getFooCount()); foo(foo_count); In this code, foo only gets called when getFooCount returns a valid value - which is the function's post-condition, so it would have thrown an exception otherwise. There are two different ways to port this to C: unsigned int foo_