File Integer Sum Assignment

For this assignment you will write a program that reads integers from an input file, and writes the sum of the integers to an output file. The name of the input file and the name of the output file will be provided as command line arguments, with the input file first and the output file second.

Use fscanf() and fprintf() for input and output. See the example code for guidance.

If your program runs without errors, there should be nothing printed to standard output, since the output of the program is being written to a file.

You can create a file for input in Atom by clicking File -> New File and then saving it in the cloned assignment directory.

For example, say you create an input file named input.txt and input.txt contains the following:

1 2 3
4 5 6 7

Then you run your program like this:

./file_integer_sum input.txt output.txt

No output should be printed, but output.txt should contain 28. You can view the output file by opening it in Atom or by printing the contents in the terminal using cat:

cat output.txt

If there are errors, your code must print an error message and return a specific exit code depending on the error. Below are the different error conditions that your program should deal with, and the exit code that should result under each condition.

• Incorrect number of arguments, exit code 1
• Error opening the input file, exit code 2
• Error opening the output file, exit code 3

You can force an error in opening the input file by providing the name of a file that does not exist. You can force an error in the output file by giving an absolute path of a file that would be written into a directory that does not exist. For example:

./file_integer_sum does_not_exist.txt output.txt
Error opening does_not_exist.txt for reading

./file_integer_sum input.txt /directory/that/does/not/exist.txt
Error opening /directory/that/does/not/exist.txt for writing

./file_integer_sum
Usage: ./file_integer_sum <input file> <output file>

Many submissions to past assignments have hardcoded the name of the executable in the usage message. It is better to let printf() insert the name of the executable for you, so that the usage message is correct no matter what it is named (it could be a.out or some other name). You can do that like this, since argv[0] is the name of the executable:

printf("Usage: %s <input file> <output file>\n", argv[0]);

Submission

Push your code to git-keeper. Your code will be automatically tested for correctness.