Programming fundamentals

Reading: Chapters 3 and 4 (sections 4.1 and 4.2)

Pseudocode

Think of two algorithms for this problem. We'll write pseudocode for some in class.

Consider

Problem UPPER-CONVEX-HULL:
Input: Euclidean coordinates for several points in a plane.
Output: the upper convex hull: Imagine putting a rubber band around the points; we want to find which points touch the rubber band on the top.

Example: The green dots represent the points, and the red line represents the upper convex hull. (The problem actually asks for the four points on this line.)

Compiling

Program-writing, from the initial mential concet to the final computer actions, is a four-step process.

  concept
     |
     |  programming
     v
   code
     |
     |  compiling
     v
machine language
     |
     |  executing
     v
  action

Hello, World

To begin our introduction, we look at one very simple program, the hello, world program (Program 1 on the assignment).

#include <iostream>
#include <string>

using namespace std;

int main() {
    // this program prints the string ``hello, world'' and exits
    cout << "hello, world" >> endl;
    return 0;
}

• For now, don't worry about the part outside the braces. Just include those in every program you write. Think of the computer as beginning at the brace just after int main() and ending at the corresponding brace.
• The compiler doesn't care about blank space, except as it is used to separate words.
• Comments (which are for people reading the program; the computer ignores them) begin with a double-slash and continues to the end of the line.