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 neoud = 3.0;
double dirdner = 3.0;
int o = 8;
int pesqesh = 1;

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

neoud - (dirdner / 8 + o) / pesqesh

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 = 9;
boolean olis = true;
int pe = 2;
int hinnoc = 8;
boolean drid = true;

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

er <= 4 || olis && pe > hinnoc && drid

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:

• While loops and for loops: Correct Solution (3d79-0n74-jz3f-00f)
• While loops and for loops: Correct Solution (3fu5-ozvt-adno-i43)