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 ent = 2;
double wanpoght = 3.0;

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

2 / ent + 8 % (wanpoght + 1) - 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 oasm = 8;
double kopa = 1.0;
int en = 9;
int porceek = 7;
int an = 7;
double intni = 3.0;

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

oasm == kopa && en < 9 || !(2 > 5) || porceek >= 0 == an <= intni

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

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 (wtsb-o58x-mtme-h4v7)
• Class relationships: Correct Solution (ri1m-ejjs-ccz1-jiub)