I need some help refactoring my solution to the problem below: Problem Statement An Association of Computer Scientists meets on a weekly basis. There is a certain number of seats in the meeting room and all members know their seats. For example, if there are 10 seats and only 5 members attending, each member will … Read more
I’m experimenting to learn flex and would like to match string literals. My code currently looks like: “\””([^\n\”\\]*(\\[.\n])*)*”\”” {/*matches string-literal*/;} I’ve been struggling with variations for an hour or so and can’t get it working the way it should. I’m essentially hoping to match a string literal that can’t contain a new-line (unless it’s escaped) … Read more
I want to create a read-eval-print loop using flex/bison parser. Trouble is, the flex generated lexer wants input of type FILE* and i would like it to be char*. Is there anyway to do this? One suggestion has been to create a pipe, feed it the string and open the file descriptor and send to … Read more
This question already has answers here: Capture console exit C# (10 answers) Closed 8 years ago. I have a little console C# program like Class Program { static void main(string args[]) { } } Now I want to do something after main() exit. I tried to write a deconstructor for Class Program, but it never … Read more
What’s the difference? Which is preferred, or when should I use each one respectively? Answer exit(1) (usually) indicates unsuccessful termination. However, its usage is non-portable. For example, on OpenVMS, exit(1) actually indicates success. Only EXIT_FAILURE is the standard value for returning unsuccessful termination, but 1 is used for the same in many implementations. So to … Read more
I’m having Lex and YACC files to parse my files (.l file and .y file). How to compile those files and how to make equivalent .c file for them in windows platform? Answer As for today (2011-04-05, updated 2017-11-29) you will need the lastest versions of: flex-2.5.4a-1.exe bison-2.4.1-setup.exe After that, do a full install in … Read more
I’ve been trying to figure out how the fork-exec mechanism is used inside Linux. Everything was going on according to the plan until some web pages started to confuse me. It is said that a child process should strictly use _exit() instead of a simple exit() or a normal return from main(). As I know, … Read more
I am looking for the R equivalent of linux/POSIX exit(n) which will halt the process with exit code n, signaling to a parent process that an error had occurred. Does R have such a facility? Answer It’s an argument to quit(). See ?quit. Arguments: status: the (numerical) error status to be returned to the operating … Read more
Can people point me to resources on lexing, parsing and tokenising with Python? I’m doing a little hacking on an open source project (hotwire) and wanted to do a few changes to the code that lexes, parses and tokenises the commands entered into it. As it is real working code it is fairly complex and … Read more
I’m currently launching a programme using subprocess.Popen(cmd, shell=TRUE) I’m fairly new to Python, but it ‘feels’ like there ought to be some api that lets me do something similar to: subprocess.Popen(cmd, shell=TRUE, postexec_fn=function_to_call_on_exit) I am doing this so that function_to_call_on_exit can do something based on knowing that the cmd has exited (for example keeping count … Read more
