CSE 333 25sp Exercise 5

out: Friday, April 11, 2025
due: Monday, April 14, 2025 by 10:00 am, No late exercises accepted.

Goals: Continue exploring multi-file C programs by adding details not part of the previous exercise: header guards, internal linkage for "private" helper functions, and using a Makefile to control building the program.

Description: In this exercise we will modify the implementation of the multi-file C program from the previous exercise. The specification remains exactly the same. The program should have the following three files (specification copied with no changes from the previous exercise, except that ex4.c should be renamed ex5.c):

• NthPrime.h: a header file, containing a single function prototype declaration for a function called NthPrime(), as well as comments above the prototype documenting how to use the function. The function should accept a single int16_t parameter, and it should return an int64_t. The function should return the nth prime number, where n is the function's parameter. Note that NthPrime(1) should return 2, NthPrime(2) should return 3, NthPrime(3) should return 5, and so on. The result of NthPrime(n) is not defined if n <= 0, and implementations do not need to check for this possibility.
  
• NthPrime.c: a file containing the implementation of NthPrime. Feel free to use the simplest possible primality testing algorithm (hint: "x is not prime if it is divisible by ..."). You may also want to define some helper functions here as well.
  
• ex5.c: a file containing a main() function that tests NthPrime by printing the input and output output of NthPrime for at least two different, non-trivial arguments (but you do not need to print an enormous number of test cases - keep it reasonable).

The differences from the previous exercise are that this time your implementation must:

• Include proper header guards in the NthPrime.h header file,
• Use static to ensure that "private" helper functions (if any) in NthPrime.c have internal, not external linkage and thus are not visible to other files, and
• Include a suitable Makefile as described below.

The Makefile must have the following properties:

• The command make should compile source file(s) as needed and then link the resulting object files to create an executable program named ex5.
• The Makefile should only recompile individual files and rebuild the program when needed and should reuse any existing .o object files or other files that are already up to date.
• Files should be compiled with the -Wall -g -std=c17 options, plus any other options needed to separately compile files (e.g., -c) and later combine them into an executable program.
• The command make clean should remove the ex5 executable file, all .o files, and any editor or other backup files whose names end with ~ (for example, ex5.c~).

In your solution to this exercise, feel free to use code from your own solution to the previous exercise, or the sample solution to that exercise posted on the course website, or both. Also, free to directly adapt the example Makefile from lecture to use here.

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Your code must:

• compile without errors or warnings on CSE Linux machines (lab workstations, attu, or CSE home VM)
• have no crashes, memory leaks, or memory errors on CSE linux machines
• have a Makefile as described above that compiles code using the gcc options -Wall -std=c17 -g.
• be pretty: the formatting, modularization, variable and function names, and so on must make us smile rather than cry. (Suggestion: see if cpplint --clint reports any problems. However, you may ignore warnings from cpplint --clint about the header guard #define name not including a full file path as long the identifier has an otherwise appropriate name.)
• be robust: you should think about handling bogus input from the user, and you should handle hard-to-handle cases (if there are any) gracefully.
• have a comment at the top of each of your files with your name, student number, and CSE or UW email address.

You should submit your exercise using the Gradescope dropbox linked on the course resources web page.