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 dut = 5.0;
double gleee = 2.0;
int bi = 6;
int stisscuomp = 8;

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

0 % dut * 0 / gleee % bi * 2 / stisscuomp

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:

double ic = 1.0;
int papath = 9;
int fe = 7;
int a = 1;
double tearo = 3.0;
double ressce = 5.0;
boolean shiu = true;

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

ic > papath != 1 > 7 == !(9 < fe) && a < tearo && 8 > ressce == shiu

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"

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:

• Booleans and conditionals: Correct Solution (5hfL-423j-8xqt-4qgd)
• While loops and for loops: Correct Solution (1980-0Lce-pe9g-jyr)