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:

int mirds = 8;
double muosrid = 5.0;
int er = 5;
int reoul = 8;

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

(mirds + 6 - muosrid % er % 5 % reoul / 4 % 9)

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:

boolean prass = false;
boolean ta = true;
double fe = 2.0;
boolean pealpre = true;
double jios = 2.0;

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

1 >= 5 || prass && ta != 5 > 4 == fe >= 4 != pealpre == (4 == jios)

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 + 5 + 6 + "7" + 8

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:

• Drawing ASTs for expressions: Correct Solution (aza1-1mkx-ui6m-xsxx)
• Class declarations and object modeling: Correct Solution (17s8-mr1v-w0cq-soLL-c)