9 + 10. Functions

Question 1

function declaration

Answer 1

• declare functions before use
• incl all info needed to use function
• provide comment w/ each function declaration

Question 2

info needed to use function

Answer 2

function data type
function name
parameters with their data types

Question 3

function definition

Answer 3

• consists of declaration + function body

- body: computes function value + returns a value unless it is a void function

Question 4

what functions can return

Answer 4

doubles, ints, chars, strings, booleans, etc

Question 5

boolean function

Answer 5

useful for abstracting complex abstractions

Question 6

parameters

Answer 6

in the declaration, the info inside () are the formal parameters of the function

Question 7

arguments

Answer 7

when calling a function, the values put into the () are the arguments passsed to the function

Question 8

zero parameters

Answer 8

eg. int f();
double g();

Question 9

when to use a function

Answer 9

• when task is easy to identify but hard to implement code

- whenever you have to write same code or v. similar code a second time (when code can be repeated)

Question 10

pass by reference (call-by-reference)

Answer 10

use of &, changes the argument

Question 11

pass by value (call-by-value)

Answer 11

no use of &, does not change the argument

Question 12

void functions

Answer 12

functions that dont return anything

Question 13

void functions syntax

Answer 13

void function_name (parameters);

Question 14

need for call-by-reference parameters

Answer 14

for when we want a function to:

• read in a bunch of data eg. read payroll details
• return multiple values eg. day, month, year
• change 2 values in tandem eg. simplify fraction

Question 15

call-by-reference parameters

Answer 15

• can update storage places
• instead of passing value into function, pass a reference to a place where value is stored
• use ampersand (&)

Question 16

using ampersands

Answer 16

• only use if you want function to change value of a variable in main
• dont use if function only needs the value of parameter