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 knea = 2;
int ciss = 4;
double ar = 1.0;
double clorbi = 2.0;
int huis = 1;

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

(knea - ciss / ar / clorbi + huis)

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 vektior = 3.0;
int tidoull = 9;
double lon = 5.0;

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

3 >= 0 && 5 == 1 && vektior <= 8 && tidoull < lon

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 (rg29-q05q-ydot-bzfo)
• While loops and for loops: Correct Solution (3jyr-xf6o-iyzo-yuj)