Drawing ASTs for expressions: Correct Solution

For each of the Java expressions below:

• Draw an AST for the expression.
• Show how the expression evaluates at each node in the tree.

Be sure that your tree accurately reflects how Java would evaluate the expression.

Part 1

Given the following variables:

double borprist = 3.0;

...draw the AST and evaluation results for the following expression:

(5 % borprist % 8) / 8

Solution

Things to double-check in your solution:

• Do you have the left and right branches on the correct side?
• Did you indicate the difference between ints and floating point values?

Part 2

Given the following variables:

int uormlan = 7;
double liococ = 1.0;
double chischu = 4.0;
boolean slic = false;

...draw the AST and evaluation results for the following expression:

uormlan < liococ || 9 > chischu && slic

Solution

Things to double-check in your solution:

• Does your tree correctly reflect the precedence of && and ||?
• Did you correctly show short-circuiting? (That is when the right branch of && or || is never evaluated because the left branch already determines the answer.)

Part 3

Draw the AST and evaluation results for the following expression:

0 + (1 + "2" + 3) + 4

Solution

Things to double-check in your solution:

• Did you indicate the distinction between ints and Strings?
• Are your left/right branches correct?

Related puzzles:

• Static and runtime types: Correct Solution (wtjr-rLbt-qmyq-cnem)
• Static and runtime types: Correct Solution (wtiq-85hf-ibzf-m72k)