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 chonsguss = 2.0;
int pedspo = 6;
double ecest = 3.0;
int otcor = 1;

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

4 + chonsguss % pedspo * 0 / ecest % 1 + otcor

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:

double shocis = 3.0;
int thaniang = 7;
double ha = 2.0;
double ia = 2.0;
int loiud = 5;
int trudjin = 6;

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

6 < 1 || 0 > shocis || (thaniang != ha && 8 < ia == (3 == 8) || !(!(loiud <= trudjin)))

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"

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:

• Variable scope and lifetime: Correct Solution (gf12-p5ij-abzn-kq91)
• Booleans and conditionals: Correct Solution (5oj5-hrxy-Lyzb-mw6x)
• Booleans and conditionals: Correct Solution (5hpv-6ye6-zxdt-1oao)