apcsp

functions

1. Avoid repeated code

2. Break program into smaller parts

   • Simplify problem solving process

1. Make program more readable

2. Functions = helps make karel turn right

Top Down Design/Decomposition

• Decomposing program into readable tiny parts

• - Big messy functions < small simple functions

• Helps solve large complicated problems

• Lets us collab by splitting problem into subproblems that can be solved independently

Comments on Code

1. Good style = clean + reasonable

2. Notes explaining the code to reader

i. Preconditions = must be true before function

ii. Postconditions = must be true after function

Abstraction

1. "Abstracting away" complex info to be relevant

2. Defines program steps, but not how exactly

i. write functions to "abstract away" picky details

AP| = Application Programming Interface

1. Set of tools for building programs

2. Karel = API built by Python that abstracts her
   code

For Loops

• repeated fixed # of times

• for i in range (#): move()

Bug

Mistake in Code

Conditionals

1. function returning a T/F answer

   • Front clear? Balls present? Facing east?

2. If/Else Statements

   • For different worlds: specific < general

3. While Loops: repeat code IF condition is true

Control Structures

1. Ask Questions: If & If/Else Statements

2. Repeat Code: For & While Loop

Debugging Strategies

• Pay attention to details (typos…)

• Question all assumptions

Error Types

1. Syntax: program no run

2. Runtime: program run then crash

3. Loop: program run then confused (no message)

Algorithms?

Step by step set of instructions to solve problem

All algorithms made with

• Sequence, Iteration, Selection (efficiency + clarity)

Sequence

step by step execution in given order / natural program flow

Iteration

repeating instructions (for/while loops)

Selection

choosing which instructions to do (if & if/else statements)

Problem Solving Process

Natural language < Pseudocode < Program

Pseudocode

Writing out algorithm plainly to help write program

Parameters : color[“red”]

• Inputs into functions

  • we can pass parameters to a function to make it do specific things