AP CSP Unit 3 Review

Which of the actions would usually be helpful in designing and developing an app?

• I and II only

• I and III only

• II and III only

• I, II, and III

Answer explanation

Consultation and communication with program users is an important aspect of program development. Incrementally adding tested program segments to correct working programs helps create large correct programs. You received feedback from your peers when you generated your idea. You also observed classmates using their apps last week.

Which of the following best describes the purpose of a design specification (aka prototype)?

• Tracking errors that arise through user testing

• Documenting comments that will need to be added to a program

• Describing the requirements for how a program will work or users will interact with it

• Listing detailed questions that will be asked of users during interviews

Answer explanation

We created a prototype of the app.

What will the “background-color” of the “topButton” be when the program is finished running?

• red

• orange

• blue

• green

Answer explanation

This is an example of sequential programming where the program statements run in order, from top to bottom. Since the last change to the “background-color” of the “topButton” is to the color blue, that is the color it will be when the program is done running.

If the user does NOT click the button what color will “topButton” be when this program finishes running?

• red

• blue

• green

• orange

Answer explanation

Since this is an example of event-driven programming, the commands on lines 4 and 5 will only execute when the user clicks the “topButton” since they are inside the onEvent block.

Since this question asks about the situation of the user NOT clicking the button, the last change to the color happens when line 2 executes and sets it to blue.

The following program is run. Then the user clicks the "topButton" button ONCE. What will be displayed in the console?

• cat bird dog

• dog cat bird

• cat dog bird

• bird cat dog

Answer explanation

Once the program is run, lines 1 and 5 will run, in that order, right away, meaning that the first two words displayed will be cat and dog respectively.

The word bird will be displayed once the user clicks the “topButton” and causes line 3 to run.

The following program is run. Then the user clicks the “bottomButton” ONCE and then clicks the “topButton” ONCE. What will be displayed in the console?

• cow pig chicken

• cow chicken pig

• pig cow chicken

• chicken pig cow

Answer explanation

Walking through the code run based on the description in the question:

Line 7 will run as soon as the program is run, displaying chicken to the console.

The user clicks the “bottomButton” ONCE which causes line 5 to run, displaying pig to the console.

The user clicks the “topButton” ONCE which causes line 2 to run, displaying cow to the console.

The following program is run. Then the user clicks the “bottomButton” TWO TIMES. What will be displayed in the console?

• apple banana cherry cherry dragon fruit

• banana dragon fruit cherry cherry

• banana dragon fruit apple apple

• banana cherry cherry dragon fruit

Answer explanation

Walking through the code run based on the description in the question:

Lines 4 and 8 will run as soon as the program is run, in that order, displaying banana then dragon fruit to the console.

The user clicks the “bottomButton” the first time which causes line 6 to run, displaying cherry to the console.

The user clicks the “bottomButton” the second time which causes line 6 to run again, displaying cherry to the console again.

Which line of code in this program is MOST likely to result in an error?

• Line 1

• Line 2

• Line 3

• Line 4

Answer explanation

When printing characters to the console, they must have quotes around them to mark them as a string. Numbers can be printed as strings as in “100” or as numbers with no quotes, as in 100.

Which of the following BEST describes the differences between sequential and event-driven programming?

• In sequential programming commands run one at a time. In event-driven programming all commands run at the same time.

• In sequential programming commands run faster than in event-driven programming.

• In sequential programming each command is run many times in sequence. In event-driven programming all commands are run a single time as an event.

• In sequential programming commands run in the order they are written. In event-driven programming some commands run in response to user interactions or other events.

Which of the following is NOT a reason to include comments in programs?

• Comments help the computer decide whether certain components of a program are important.

• Comments help programmers debug issues in their own code

• Comments help document how code was written for other programmers to use

• Comments enable programmers to track their work throughout the development process