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 tasmed = 9;
int e = 4;
int qesh = 2;
int adveck = 7;

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

9 + tasmed / e - qesh * 0 % 4 / adveck

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 er = 2;
double nesia = 4.0;
double veac = 1.0;
boolean orhad = true;
int ae = 7;
boolean i = false;

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

er != nesia || veac < 7 || orhad == (9 == 7) == 3 <= ae == !i

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:

• While loops and for loops: Correct Solution (1jd6-an9f-eijr-y11)
• Drawing ASTs for expressions: Correct Solution (b5fi-5cz3-L1nf-dns2)