Meaning of Exit Code 11 in C?

Question

What's the general meaning of an exit code 11 in C? I've looked around and can not find a definitive answer so I thought I would ask here. It comes when i try to add an element to a vector.

Answer 1

You didn't find a definitive answer because there isn't one. It's up to the author of the program to decide what exit codes they wish to use. Standard C only says that exit(0) or exit(EXIT_SUCCESS) indicate that the program is successful, and that exit(EXIT_FAILURE) indicates an error of some kind. (Returning a value from main is equivalent to calling exit with that value.) Most common operating systems including Windows, Linux, OSX, etc. use 0 for success and values from 1 to 255 to indicate errors; still choosing between error codes is up to the application writer, the value 11 isn't anything special.

Under Linux and most other Unix variants, the signal number 11 indicates a segmentation fault, as remarked by Kerrek SB. A segmentation fault happens when a program makes some kind of invalid memory access, so it's a plausible consequence of accessing an array out of bounds, or an error in pointer arithmetic, or trying to access a null pointer, or other pointer-related errors. Signal 11 is not the same thing as exit code 11: when a program dies due to a signal, it's marked as having been killed by a signal, rather than having exited normally. Unix shells report signals by reporting an exit code which is the signal number plus 128, so 139 for a segmentation fault.