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 ceco = 6;
int ti = 3;

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

7 % (2 * ceco / ti / 4)

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 thradscis = 3;
int sandu = 8;
int e = 2;
int bracmie = 9;
int giegoc = 9;

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

!(thradscis <= sandu) || (e >= 3 && 5 >= 8 && bracmie < giegoc)

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:

• Class relationships: Correct Solution (rjvu-hzm9-7mmt-5ft7)
• While loops and for loops: Correct Solution (358q-8eaz-u1mh-srg)