Great C programming funHEADmaster

Excellent fundamentals and displine training, many tools and techniques
exercises: gdb, emacs, valgrind, git

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+For this problem, we will be writing a function which takes
+two rectangles, determines the region in which they overlap
+(which is also a rectangle), and returns that region.
+
+Before proceeding, think about what the corner case(s) [no pun intended!]
+in this problem might be.
+
+ 1. Open the provided file called "rectangle.c"
+
+ 2. In the "rectangle.c" file, define a struct for rectangles
+    which has 4 fields: x, y, width, and height.  Each of these
+    fields should be an int.  Use typedef so that the typename
+    "rectangle" refers to your struct.
+
+ 3. One corner we might have to deal with is if the rectangle's
+    representation is non-standard: if the width or height are 
+    negative.  One way to deal with inputs that come in non-standard
+    formats is to "canonicalize" them---convert them to the standard
+    (or "canonical") representation.   First, write the function
+
+      rectangle canonicalize(rectangle r);
+
+     which takes a rectangle, and "fixes" its representation 
+     by ensuring that the width and height are non-negative (and
+     appropriately adjusting the x and/or y co-ordinate).  That is,  
+     if your canonicalize function were passed a rectangle with
+        x=3, y=2, width=-2, height=4
+     then it should return a rectangle with
+        x=1, y=2, width=2, height=4
+     as these both describe the same rectangle, but the later is
+     in a canonical representation.
+ 
+     It may be a good idea to stop and test this function
+     before proceeding.  Compile and run your code.
+     The main function we have provided should be useful,
+     as it canonicalizes the rectangles it prints.
+
+  4. Now, write the function
+      rectangle intersection(rectangle r1, rectangle r2)
+     which takes two rectangles (r1, and r2), and returns
+     the rectangle representing the intersection of the two.
+     
+     Note that there is a corner case where the correct answer
+     is "no intersection".  We have not learned how to represent
+     "no such thing" yet, but we will consider a rectangle with
+     both width and height equal to 0 to mean "no such rectangle".
+     
+     We will consider a rectangle to have one (but not the other)
+     of width or height equal to 0 to be an appropriate answer
+     when rectangles share an edge but do not overlap.  For example,
+      x=0,y=0,width=1, height=1
+     and
+      x=-1,y=1,width=3,height=2
+     Should result in the "rectangle"
+      x=0,y=1,width=1,height=0
+   5. We have provided a main function which tests your code,
+      as well as correct output (rectangle_ans.txt) to diff against.
+
+   6. Submit your code
+
+Hint:
+     Do Step 1 (work an example yourself) four or five times.
+     Draw a variety of different ways that rectangles can overlap.
+     Use these to help  you think abou the general algorithm for how
+     to determine their overlapping region.