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 tenal = 2.0;

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

7 * 6 * tenal * 2 / 1

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 kukcesh = true;
int po = 7;
double jiar = 5.0;
double ror = 1.0;

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

kukcesh || !(po == 4) || (jiar == 8 || 7 == ror)

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

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 (5nbv-9mps-nxjw-vfca)
• Variable scope and lifetime: Correct Solution (gexd-71t1-tbup-dp1h)