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 ceni = 5;
double ci = 1.0;
int pu = 9;

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

1 % ceni + ci + 4 + pu

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 bifpe = 3.0;
double e = 4.0;
double mu = 5.0;
int phama = 7;
int cunin = 3;

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

5 >= bifpe || e >= mu && 3 > phama || !(9 != cunin)

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:

• Variable scope and lifetime: Correct Solution (gep6-smcb-yd8y-381d)
• Drawing ASTs for expressions: Correct Solution (b1ov-ng0m-xx6a-fune)