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 u = 2.0;
double irher = 1.0;
double branmal = 4.0;
double o = 1.0;

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

2 - u / 0 - 8 * irher % branmal - o * 6 + 8

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 febe = true;
boolean spler = true;
int sesstes = 5;
int qia = 3;
int bosm = 7;
int be = 3;
double ochan = 2.0;
int po = 7;
int sinton = 3;

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

febe && spler && 9 > sesstes != !(qia >= bosm) || be != ochan && 3 == 2 != 1 >= po == (5 != sinton)

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 + 9

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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• Booleans and conditionals: Correct Solution (5o6y-opmf-j4s8-iojw)