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 repio = 3;
int ipriacs = 7;
double grewioth = 2.0;
double otgid = 5.0;
double grirtar = 3.0;

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

repio % (7 + ipriacs) - 6 + grewioth - 2 / otgid * grirtar

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:

int rirved = 5;
double phreich = 5.0;
double de = 2.0;
int raeong = 9;
double sondri = 4.0;
int ur = 2;
double qamprin = 3.0;
int e = 3;

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

rirved <= phreich || 6 != 9 == (de != raeong) || sondri > ur || 4 < 9 && 5 < 3 && qamprin != e

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 + 8

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:

• Class relationships: Correct Solution (rguf-o01L-ska2-maxk)
• Booleans and conditionals: Correct Solution (5h35-jrcs-5nun-qd45)
• Drawing ASTs for expressions: Correct Solution (b1dp-0axs-bb4n-ixnw)