Do not use the bitwise AND (&, ampersand) or bitwise OR (|, pipe) operator in a conditional expression because this typically indicates programmer error and can result in unexpected behavior. Use & or | only for bitwise operations and use && or || only for logical operations.

Noncompliant Code Example

In this noncompliant code example, a bitwise expression is used in a conditional expression.

if (!(getuid() & geteuid() == 0)) { 
  /* ... */ 
} 

Compliant Solution

This compliant solution uses the && operator for the logical operation within the conditional expression.

if (!(getuid() && geteuid() == 0)) {
  /* ... */
}

Automated Detection

Tool	Version	Checker	Description
Coverity Prevent		CONSTANT_EXPRESSION_RESULT	can detect the specific instance where bitwise operator is used in place of logical operator or vice versa. The behavior might be desirable in some situation, so further verification is necessary.

Related Guidelines

ISO/IEC TR 24772 "KOA Likely Incorrect Expressions"

MITRE CWE: CWE-480, "Use of Incorrect Operator"

Bibliography

[Hatton 1995] Section 2.7.2, "Errors of omission and addition"

      03. Expressions (EXP)      EXP18-C. Do not perform assignments in selection statements