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 ritvur = 8;
int eaa = 6;
double thost = 4.0;
int dablul = 4;

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

4 % (5 * ritvur % eaa) / thost + dablul / 2

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 siet = 3.0;
double iet = 2.0;
int hepool = 7;
double viil = 1.0;
double bresh = 1.0;
int frip = 4;
int ma = 4;

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

5 != siet == 5 <= iet || (hepool < viil || bresh != frip && 8 <= 9) || !(0 == ma)

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

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 (rh2q-7esf-zjz2-gu0w)
• Class declarations and object modeling: Correct Solution (17t6-qg8j-kzo4-tuxp-j)