The test is open-everything with the sole limitation that you neither solicit nor give help while the exam is in progress.

Submit all answers on these exam sheets. No extra sheets are allowed. You have only thirty minutes to complete the exam. I don't suspect many people will finish all the problems; the intent is to make sure the people most familiar with the material get the best grades.

1. Write a C function that takes in two strings and the returns the string with the characters of each interleaved, as in the following examples:
   • interleave("dog", "rat") == "droagt"
   • interleave("capybara", "it") == "ciatpybara"
   • interleave("java", "suckzzz") == "jsauvcazzz"
2. Write a C function (call it dot_product) that takes in two arrays of doubles, and returns the sum of the products of corresponding items. Note that because this is C, your function will need to take in a third parameter, namely the size of the arrays. Example: if a were the array [5.0, 3.0, 1.0], and b were the array [6.0, -3.0, 2.0], then dot_product(a, b, 3) = 23.0.
3. Write a complete C program that writes, to standard output, its longest commandline argument. If there are multiple longest arguments, just write one of them.
4. Write a C function, from scratch (that means no library functions), that returns a substring of a string, given the first index (inclusive) and the last index (exclusive). One other rule: do not access individual characters of the string via array indexing; in other words you can't write expressions like s[i]. Instead, make use of the fact that a string is really a pointer to its first element, and adding one to a character pointer makes it point to the next character in the string. Examples:

       substring("snoopdog", 2, 6) ==> "oopd"
       substring("snoopdog", 32, 456) ==> ""
       substring("snoopdog", -5, 2) ==> "sn"
   

5. Write a C function that takes in a string s and an integer k, and returns a new string containing every kth character in s. For example:

      f("Go to the beach", 3) ==> "Gtt a"
      f("Whatever", 2) ==> "Waee"
      f("This function is really weird", 5) ==> "Tfisle"