What is Computer Programming?

Think about a hammer.
- What is a hammer?
- What is the primary task of the hammer?
- Can you use a hammer to do other things?
  - IE, can you open a can of soup with a hammer?
- How much training is there to learn to use a hammer?
What is a computer?
- A programmable device that can store, retrieve, and process data.
  - This definition is from the book.
  - It is in a "blue box".
  - Definitions in these boxes are good things to know.
- Programmable?
  - A program is a sequence of instructions that can be performed by a computer.
  - Programs are usually written to solve a problem.
  - They are written in a programming language, but more on that, well the rest of the semester.
- Computers, along with attached devices such as robotic arms, cars, sensors, ... are just really complex tools.
  - Programs allow these tools to solve many complex problems.
  - So they are way more complex to learn to operate than a hammer.
Programming: an example
- To start
  - I'd like to step through the entire process.
  - You need to understand this process, but not all of the details.
  - We will work on those as we go along.
- I would like to write a program that computes the price of taking a group of people to the movies. Consider the following made up prices:
  - An adult ticket is $8
  - All other tickets are $6.50
- Write a program that will compute the total cost and provide an itemized breakdown of the cost.
  - ```
  For 2 adults and 3 others the price will be:
      Adult Tickets        $16.00
      Other Tickets        $19.50
  
      Total                $35.50 
```
- Notice this example is only for the instance of the problem where there are 2 adults and 3 children.
- This will not always be the case, we want our program to work for any number of children and adults.
- Do you understand the problem?
  - Do you see how the example was computed?
- Can you write instructions for a person how to do this?
An Algorithm Is a step by step procedure for solving a problem in a finite amount of time. (Blue box definition)
Can we write an algorithm for problem?
- ```
Get the number of adults
Get the number of others

Compute the cost for the adult tickets   
Compute the cost for the other tickets
Compute the total ticket cost

Print the number of people going to the movies
Print the total ticket cost
Print the total cost 
```
- Note there are some things here you normally don't think of
  - Get the number of people.
  - Print the results.
- Could you do some of these steps in a different order?
  - Yes some of them, but not others.
- Could you skip any of these steps?
- Does the algorithm work for the given input data?
- Can you think of another test case for the algorithm?
- Can you use this algorithm to test to see if
  - You understood the problem?
  - Your solution works?
On page 4 there is one programming process diagram.
- This is not the only programming process, but it is a start.
- Note first steps

How did we use this process?

Look back at the notes:
- Understand the problem.
- Write an algorithm.
- Check the algorithm?

I expect you to use this process.

If nothing makes sense right now, this is a place to start.
If everything is overly-easy right now, don't worry things will get much more complex. This process works.

Just to be explicit, when writing a program:

Make sure you understand the problem.
- If you do not, ask questions.
Write an algorithm.
Test your algorithm, the move on only when it works.

We will discuss algorithms more as the class goes along.