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 thiiri = 1.0;
double es = 5.0;

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

thiiri + 2 % 5 / es

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 centte = 6;
double ao = 5.0;

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

centte <= 9 && ao >= 1 || 4 < 7

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

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 (3q23-jdpn-kj2x-p5s)
• Variable scope and lifetime: Correct Solution (gfap-dnyL-a2k2-ncxw)
• Class declarations and object modeling: Correct Solution (17wo-pnk6-ubaa-7w0a-w)
• Variable scope and lifetime: Correct Solution (getn-yjn6-hqwd-tw5n)
• Closures and event handling: Correct Solution (Lzuk-vq0x-g1wb-14vh)
• Drawing ASTs for expressions: Correct Solution (b2di-r4v9-rbsn-9pjo)
• Booleans and conditionals: Correct Solution (5Lkh-1cx2-ddri-e2p8)
• Closures and event handling: Correct Solution (Lw1s-50du-1bd7-edbq)
• Booleans and conditionals: Correct Solution (5muq-8hgk-ybom-r5t1)