unit 5 AP compsci

why do we use functions

helps us understand the code easier

makes code less repetitive and more organized

makes code reusable

Parameters

The inputs/what goes into a function

Order matters

local variables

defined inside a function/loop and can only be used inside that function/loop

global variables

can be used anywhere in the code

ex: constanants

scope

the area of code that a variable can be used in

why do we need scope

differentiate variables with the same name in different parts of code

(cannot have 2 variables with the same name within the same scope)

What does API stand for

Application Programming Interference

what does api do

Set of tools for buliding programs

Helps two programs connect or communicate with each other

Helps devices connect and connects devices to programs

API examples

spotify, twitter

return value

returns the value when the function is called, does not print value unless println is used

What part of the function is bolded?

function start(){

var numApples = 4;

println("Before: " + numApples);

var twiceAsMany = doubleNumber(numApples);

println("After: " + twiceAsMany);

}

function doubleNumber(x){

var doubledX = 2 * x;

return doubledX;

calling the function

What part of the function is bolded?

function start(){

var numApples = 4;

println("Before: " + numApples);

var twiceAsMany = doubleNumber(numApples);

println("After: " + twiceAsMany);

}

function doubleNumber(x){

var doubledX = 2 * x;

return doubledX;

defining the function

What part of the function is bolded?

function start(){

var numApples = 4;

println("Before: " + numApples);

var twiceAsMany = doubleNumber(numApples);

println("After: " + twiceAsMany);

}

function doubleNumber(x){

var doubledX = 2 * x;

return doubledX;

function body

What part of the function is bolded?

function start(){

var numApples = 4;

println("Before: " + numApples);

var twiceAsMany = doubleNumber(numApples);

println("After: " + twiceAsMany);

}

function doubleNumber(x){

var doubledX = 2 * x;

return doubledX;

return value statement

What part of the function is bolded?

function start(){

var numApples = 4;

println("Before: " + numApples);

var twiceAsMany = doubleNumber(numApples);

println("After: " + twiceAsMany);

}

function doubleNumber(x){

var doubledX = 2 * x;

return doubledX;

parameter

syntatic validation

enforces correct syntax on structures fields

ex: 9 digits in SSN, date in correct form

semantic validation

enforces the correctness of the values in the specific business context

ex: start date is before end date