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CIS241

CIS241 - F2025 Final Exam Study Guide

All material from the midterm onward (i.e., starting with regex) is valid for questions

  • In-class discussions/demos
  • Homeworks
  • In-class assignments
  • Slides

Things to know

  • You can bring a 1-page cheat sheet, front and back. You’ll need to turn it in with your exam, so if you want it back put your name on it.

  • The exam is hand-written - no devices allowed.

  • The exam will comprise a number of theory (what you understand) and practical (do a thing) types of questions.

    • For the practical questions, I’ll provide a reference guide on the back of the exam.

Sample topics

Note - this is not comprehensive - anything is valid from the slides/assignments

  • What is the purpose of regex? How could you use it in a script?
  • What is the purpose of using tmux/screen? Give an example of its use.
  • What is the purpose of compiling a C program? How is a compiled file different from programs in languages like Java or Python?
  • If I build a binary file with gcc, can I simply give it to you to run? What would I have to do to make sure it works for you?
  • What is the purpose of a #include block? What happens if I try to call printf without #include <stdio.h>?
  • What is a preprocessor directive?
  • Are the semi-colons actually required?
  • How do you run a program?
  • How do you compile a program? Compile with extra warnings displayed? Compile to a named binary file?
  • Why do we worry about how many bits a variable has? How large of a number does a 32-bit unsigned integer allow? What if it were signed?
  • Boolean doesn’t exist by default - describe two ways you could use a Boolean in C.
  • What is a pointer? Why bother using one? Give an example.
  • How can you be sure that dynamically-allocated memory is initialized to 0? To another value?
  • What are int argc, char* argv[]?
  • How do you convert a char to an int?
  • What is the difference between & and * with respect to pointers?
  • What is variable scope?
  • Describe what the stack and what the heap are.
    • If I use statically-defined variables (e.g., int x), where is that memory stored?
    • If I use malloc, where is that memory stored?
  • Be able to follow a C program and describe what is happening (could be looping, could be pointer math, etc.).
  • What is the difference between a function prototype and function definiton?
  • What is pass-by-reference and pass-by-value? What does C natively do (i.e., without pointers)?
  • What is the purpose of using free to clear up memory created with malloc/calloc?
  • What are some memory-specific concerns one would have with reading user input?
  • What is the purpose of a struct? What is the purpose of a union?
  • Why would we use typedef?
  • What is the purpose of debugging? Why would we use gdb over trace debugging (i.e., print statements)?
  • What are header guards? Why do we need them?
  • Are 2D arrays always contiguous in memory? Is it a problem if they aren’t? How would you access data if they weren’t (i.e., if you couldn’t do arr[1][4])?
  • What is the purpose of a makefile? Describe three actions you can do with it.
  • Describe two uses of the string library.
  • Describe how you would read and write from/to a file.
  • What is the purpose of an enum?

Sample practical questions

Note - this is not comprehensive - anything is valid from the slides/assignments

  • Define a regex that matches an input (using extended regular expressions as we did in class)

  • In C, be able to:

    • Read and use command-line arguments
    • Print output to the terminal (ints, strings, chars, etc.)
    • Use preprocessor directives to define variables, check if they exist, etc.
    • Create, initialize, and use a 1D array
    • Create, initialize, and use a 2D array
    • Create dynamic memory of a specified size and type.
    • Create and use a header file with header guards
    • Handle user input (characters, integers, or strings)
    • Create and use a struct
    • Define and call functions
    • Read and write a file
    • Use control/loop statements (if, for, while, etc.).
    • Create a variable, create a pointer to that variable, and update the original variable’s value via the pointer.
    • Access an array via index and via a pointer
    • Pass a struct to a function and update it
    • Define a makefile that builds a target binary, builds an intermediate binary, and cleans up its mess.