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 amac = 1.0;
double ni = 1.0;
int cesscing = 7;
double ridel = 2.0;

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

(amac - ni - 5 - 5) - cesscing % ridel

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 kiostmeps = 5.0;
int stassis = 2;
boolean mu = true;
boolean gedsplor = false;

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

!(4 <= 7) != kiostmeps < stassis == mu != 7 < 6 && gedsplor

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:

• Variable scope and lifetime: Correct Solution (geps-obmz-gony-dvze)
• Drawing ASTs for expressions: Correct Solution (b5yp-iii9-eL66-kwj0)
• Class relationships: Correct Solution (rkhL-v370-5Lq3-r64g)