Boolean Compare With Literal

ID

csharp.boolean_compare_with_literal

Severity

low

Remediation Complexity

medium

Remediation Risk

low

Remediation Effort

medium

Resource

Code Smell

Language

CSharp

Tags

code-style, suspicious-comparison

Description

Reports uses of == or != to compare a value against the boolean literals true or false. Such comparisons are redundant: a boolean expression can be used directly or negated.

Rationale

if (flag == true) is just a wordier if (flag), and if (flag == false) is if (!flag). The extra comparison adds noise and is a frequent source of the classic typo where == is mistyped as = (an assignment) — a mistake the negation form cannot make. Using the boolean directly is shorter, clearer and safer.

return flag == true;     // FLAW — write: return flag;
return flag != false;    // FLAW — write: return flag;
return true == flag;     // FLAW — literal on the left
return flag;             // OK — used directly
return x == y;           // OK — not a boolean literal

Remediation

Use the boolean expression directly. Replace flag == true with flag, replace flag == false or flag != true with !flag, and replace flag != false with flag.

References