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:

double qopess = 2.0;
int ivad = 5;
int hec = 3;

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

qopess / (6 / ivad + hec)

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 mipism = 2;
int vecnir = 2;
int dredbio = 3;
int thion = 8;

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

mipism >= vecnir || dredbio != 8 && thion < 0

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

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 (38nx-q4ps-grdz-ryb)
• Drawing ASTs for expressions: Correct Solution (b35d-rzmj-6q05-b984)