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 natun = 4.0;

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

3 / 1 / 1 + natun * 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:

double stroc = 3.0;
int tacspud = 1;
double nelhir = 2.0;
double supen = 5.0;

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

3 != stroc || 6 == 2 || tacspud < 5 || nelhir > supen

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 (5Lud-51zz-kitg-q0m0)
• Booleans and conditionals: Correct Solution (5i5z-fuz5-w4o7-pd9y)