9. Programming (4)

Question 1

Why are functions useful?

Answer 1

1. They let us split the code into smaller subsections which are easier to understand.
2. Let us make units of code (our functions) that can easily be reused.

Question 2

How to define a function called myFunction?

Answer 2

int myFunction(int parameter1, float parameter2)
{
// write the function body in here
return intVal;
}
Where you can have as many or few parameters as you want and the return value has to be of the same type as the header.

Question 3

How to write a function that will add 2 numbers?

Answer 3

int add(int number1, int number2)
{
int answer;
answer = number1 + number2;
return answer;
}

Question 4

Can you show the newly defined add function being used?

Answer 4

int sum;
sum = add(4,7); // sum is set to 11
sum = add(5,6,7); // ERROR - needs 2 parameters.

Question 5

How to define a function that will flash an LED?

Answer 5

void flash(int interval)
{
digitalWrite(LEDpin, HIGH);
delay(interval);
digitalWrite(LEDpin, LOW);
delay(interval);
return; // this line is optional because no return value
}

Question 6

Example usages of flash function?

Answer 6

flash(1000); // a slow 1 sec flash
flash(100); // much faster
flash(); // ERROR - need a parameter

Question 7

What does void return type mean?

Answer 7

No return statement is required.

Question 8

what can the for loop be used for?

Answer 8

repeating an action a number of times:
for (A; B; C)
{
// things to be repeated
}

Question 9

what are A B and C in the above question?

Answer 9

• A is the variable initialisation for the loop
• B is the continuation condition
• C is the variable update

Question 10

how does:
int x = 0;
for (int i=0; i

Answer 10

int i=0 - this initialises an integer variable called i to be 0.
i

Question 11

how to work out factorial 5 using a for loop?

Answer 11

int x = 1;

for (int i=1; i

Question 12

what does for(; ;) do?

Answer 12

creates an infinite loop

Question 13

how to get out of an infinite loop?

Answer 13

use break keyword; very useful if combined with an if statement.

Question 14

what is a better way of setting up a loop which stops when something happens?

Answer 14

the do.. while() loop does something(s) as long as a condition holds. 
do
{ // things to repeat
}
while(condition)

Question 15

what are the numbers for false and true?

Answer 15

false - 0

true - 1