Lecture 23 – Nov 4th, 2019


  1. Log in to clyde.
  2. $ cp -r ~steve/ex/funptr .


  1. Look at fold.c. The foldl() function at the top of the file is an instance of a fold. It takes an array of integers (and its size), an initial value, and a pointer to a function of two ints that returns an int. It iterates through the array, applying the function to initial and the next element in the list, updating initial each time.

    Write a function add such that foldl(num, arr, 0, add) computes the sum of the num integers in arr. Have main print out the result of that.

  2. Write a function mult that you can use with foldl to produce the project of all the integers in the array. Print that result out too.
  3. Do the same thing but with min and max to compute the minimum and maximum. You may want to use INT_MIN and INT_MAX.
  4. Write a function print that you can use with foldl to print out (via printf(3)) each of the elements in the array.

    When you run your code, you should get something like this.

    $ ./fold
    array: -8 2 5 19 20 -72
    sum: -34
    product: 2188800
    min: -72
    max: 20
  5. Look at courses.c. Add your other courses to the array. Implement the appropriate comparison functions to be used with qsort(3) to sort the list of courses by (1) start time, (2) department and number, and (3) department and number but have CSCI courses first. Print out the course list after sorting by each of these using the provided print_courses().