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 ce = 4;
int qipir = 5;

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

9 + ce + qipir

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 clotis = 6;
int palpla = 2;
int nongbi = 8;
double donghioss = 1.0;

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

clotis <= palpla && nongbi >= donghioss

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

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 (14pe-2erg-r4s1-0L5)
• Drawing ASTs for expressions: Correct Solution (b407-p6bi-3zw1-grv3)