CSC 270
Homework 6

Assigned Nov. 6, due Nov. 13

In this assignment, you'll basically re-do homework 2 and homework 3 in C. Most of the code you wrote for those assignments should still work; it'll need only minor modifications to become legal, working C code.

Write a C program that reads in an int, then that many double numbers into an array, prints their sum and average (appropriately labelled), and prints out how many of them are positive. It will then sort the array (using bubble-sort or some other sorting algorithm of your choice) and print out the sorted array.

Each of the following tasks should be done by a function to which the array (and its size) is passed:

• read the doubles into the array
• compute the sum
• count how many are positive
• sort the array
• print the array

For example, if the input were
5 3.7 5.2 -4.7 -62 14.7
the output might be
Sum: -43.1
Average: -8.62
3 of your 5 numbers are positive.
After sorting, the numbers are...
-62 -4.7 3.7 5 5.2 14.7

Also turn in sample runs with well-chosen test cases.

Points to remember:

• Variables cannot be declared in the middle of a function; all the variable declarations for a function must come before any of the executable statements.
• There is no iostream, no cout and no cin; instead, we #include <stdio.h> and use the standard I/O functions printf and scanf. Note in particular that scanf expects pointers to all of its arguments (except character strings, which are already pointers). See the textbook, or log onto any Unix machine and type "man 3 printf" or "man 3 scanf" to learn more about these functions.
• There is no const declaration; instead, C programmers use the preprocessor directive

  #define VARNAME value

  which creates a compile-time constant named VARNAME (you can name it anything you want, but the convention is to use all upper-case letters) which stands for the specified value.
  Note also that the #define directive is not a statement, so it does not end in a semicolon. It should be on a line by itself. Technically, it can appear anywhere before VARNAME is used, but the convention is to put such directives near the beginning of the file, before any variable or function declarations.
• There are no reference parameters. If a C programmer wants to pass something that can be changed by the function, (s)he'll pass a pointer to the object (e.g. the scanf function mentioned above).
• The default type for floating-point numbers is float, not double. You can still work with doubles, but some built-in functions need to be specifically told that you're doing so.
• There are no classes or methods, but I don't think any of you used classes or methods for HW2 or HW3 anyway.
• There are probably other things I've forgotten; I'll try to add them here as I think of them....