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 pleapleou = 1;
double du = 1.0;
int edfriap = 6;
double ca = 5.0;
int omod = 6;

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

9 % 6 * (pleapleou % du) - edfriap - ca / 1 + omod

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:

boolean tred = false;
boolean wopre = false;
double iean = 3.0;
double he = 1.0;
boolean ufi = false;
int som = 6;

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

!tred || 9 > 5 == wopre != 7 < iean == ((he == 4) && ufi == !(6 <= som))

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" + 8

Solution

Things to double-check in your solution:

• Did you indicate the distinction between ints and Strings?
• Are your left/right branches correct?

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• Drawing ASTs for expressions: Correct Solution (b3a6-9wxj-001p-bogi)
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