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 agioucs = 4.0;
double skotont = 1.0;
int sprinpi = 8;
int an = 4;

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

1 % 7 % agioucs + skotont + sprinpi + an

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 hesid = 3;
boolean daspit = false;
double dilan = 4.0;
double ri = 1.0;
double osunt = 3.0;

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

3 < hesid == daspit || dilan > ri != 5 >= osunt != 8 < 2

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"

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:

• Class relationships: Correct Solution (rjcf-yvqd-7n19-038h)
• While loops and for loops: Correct Solution (3125-d2cs-Lk6v-bLu)