Exceptions

• Tools: the work on Unix server machines is done by connecting to them remotely. This department offers two servers to connect: neptune.cs.kent.edu and poseidon.cs.kent.edu. You can use either. There are two common programs (clients) to connect to the server: ssh or putty. Both are available from the start-menu of the lab machines. You can use either. The client provides a command-line interface to the servers. A program that interprets your command, called shell, presents a prompt similar to
  neptune%
  signifying that it is ready to accept your commands. In Unix, files are organized into directories (folders) which may contain subdirectories (subfolders). The shell keeps track of the current working directory to which default commands such as copy or create subdirectory apply. A useful command is ls that lists all the files and subdirectories of the current working directory. The navigation along the directory tree is done using cd command that changes the current working directory. The creation of files and subdirectories is done through command-line interface. See a quick guide to Unix commands below.

  Once connected you need to use an editor to input you program, use the g++ to compile it, document your actions, then use subversion to submit it.

  • Inputting your program: There are two most commonly used Unix editors emacs and vi (or vim, which is an extended version of vi). You can use either of them.

  • Compiling your program: You need to input the command to compile your program at shell prompt. Below command compiles a c++ file exceptions.cpp and produces an executable exceptions:
    g++ -o exceptions exceptions.cpp

    If the compiler outputs errors, you need to use the editor to remove them. If the program compiles successfully, you can execute it by typing the name of the executable at the prompt.

  • Documenting your actions: Unix command script presents a new prompt and then records everything that is input or output to the screen in a file called typescript Program script stops the recording after command exit is executed.

    To prove that you used Unix tools, as part of your project submission, you need to submit typescript file with the record of at least one successful compilation of your program (the execution of the compiler on your source code file).

  • Using subversion: Subversion has a Unix command-line interface that can be used to submit your program. The command to invoke subversion is svn. In particular, you need to check out your project directory tree from the repository, add the directory for the new project to the local copy of the tree, inform subversion that new files are under subversion control and then commit the changes back to the subversion repository. The sequence of commands is as follows:
    • svn checkout http://classes.cs.kent.edu/courses/cs23021/svn/SECTION/USERID
      this creates a directory USERID with subdirectories for all your projects.
    • mkdir USERID/Lab13_Exceptions
      creates a new subdirectory for the new lab.

    • cp exceptions.cpp typescript USERID/LAB13_Exceptions
      copies the files from the current working directory to the new lab directory

    • svn add USERID/Lab13_Exceptions/
      informs subversion that the new directory and all the files there are under its control

    • svn commit USERID/ -m "committing the Exceptions lab"
      stores the new files into the subversion repository. The last option (after -m) is an arbitrary string.

  Refer to the below quick reference guides for unix, editor, and subversion commands.

  Unix Tools Reference Guides

  • linux, unix
  • emacs
  • vi, vim
  • subversion

• Project assignment: Create a file exceptions.cpp. Implement a function safeNumberPrint(const string) that that accepts a string as a parameter, checks if it is an integer and then prints it. If the parameter is not an integer, the function throws notInt exception. The exception type is to be implemented as an empty class: class notInt{}; The function itself should not catch the exception.

  Hint: If the string contains an integer, each character of the string has to be a digit. To check if a character is a digit, use isdigit() function. Here is an example usage. Recall that string characters can be accessed the same was as array elements.

  You main() function should input a string and then invoke safeNumberPrint() function for the number to be printed. main() should also catch the exception thrown by the function. In case the input is not an integer, the program should print an information message and quit.