VLSI DV Interview Puzzles · All levels

Case-Sensitive vs Case-Insensitive Compare

What do these boolean checks print?

Puzzle

Difficulty: Easy · Puzzle 3 of 6 · Topic: String and Casting Puzzles

What do these boolean checks print?

Code

systemverilog

module p3;
  string a = "Reset";
  string b = "reset";
  initial begin
    $display("eq=%0d", a == b);
    $display("compare_eq0=%0d", a.compare(b) == 0);
    $display("icompare_eq0=%0d", a.icompare(b) == 0);
  end
endmodule

Hint

`==` and `compare` are case-sensitive. `icompare` ignores case.

Step-by-step solution

diagram

1) `a == b` is false because uppercase R differs from lowercase r.
2) `compare(...) == 0` is also false for same reason.
3) `icompare(...) == 0` is true because it performs case-insensitive comparison.

Answer

Answer: eq=0, compare_eq0=0, icompare_eq0=1

Why candidates get it wrong

Candidates often remember one compare API and assume all string compare methods share case behavior.

Interviewer follow-up

Which method would you use to implement case-insensitive sort ordering?

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