Top down programming

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Fallacy: You should require beginning programming students to use top-down programming.
Problem solving in computer science is best done using top-down programming.

top-down programming
goal-driven programming
backward-chaining logic

Why do many computer science programs require beginning students to do "top-down programming"?

Question to famous computer scientist Tony Hoare (British computer scientist) . Why is it so hard to teach (or require) beginning programmers top-down programming?

You cannot teach beginners top-down programming, because they don't know which end is up. Tony Hoare.

Problem-solving methodology:

Identify the problem.
Define the problem.
Design top-down solution (decomposition).
Implement bottom-up implementation (composition).
Evaluate the results.

Compare to Waterfall method, SDLC (Systems Development Life Cycle), etc.

More: Tony Hoare

Fallacy: One should implement a computer program in a top-down manner.
The phrase "top-down programming" is deceptive. Have you ever tried to write a program "top-down"?

Do it once and you will see that it does not work very well. The phrase "top down programming" refers to a "top-down program design" and then a "bottom-up program implementation".

Many people try to do "top down programming" by doing "top-down coding".

Some teachers who have never really used the method will teach this fallacy to their students. How would you define a "programmer".

Divide each difficulty into as many parts as is feasible and necessary to resolve it René Descartes (French philosopher, mathematician and statistician)

More: René Descartes

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1. First decision

2. Second decision

3. True positive

4. True negative

5. False positive

6. False negative

7. Decision tree

More: Divide and conquer

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1. Maze 1

2. Maze 2

3. Maze 3

4. Maze 4

5. Maze 5

6. Maze 6

7. Maze 7

8. Maze 8

9. Maze 9

10. Maze 10

11. Maze 11

12. Maze 12

13. Maze 13

14. Maze 14

15. Maze 15

Web site:

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Java
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More: Divide and conquer

A divide and conquer problem solving method starts with a goal.

The problem is broken down in a top-down or backward-chaining manner as part of the solution design.
The solution is implemented in a bottom-up or forward-chaining manner as part of the solution implementation.

At each point in the implementation, unit testing is added for each part and abstractions made as needed.

More: Divide and conquer

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1. Direct to goal

2. Indirect to goal

3. Missing goal

4. What goal?

A top-down design insures one will get to the goal.

A bottom-up design may require extra work and may not get to the goal.

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1. Top down

2. Backward chaining

3. Top down - flipped

4. Backward chaining - flipped

There are various names for a top-down backward-chaining divide and conquer problem solving strategy.

More: Divide and conquer: top-down and bottom-up