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org.sonar.l10n.java.rules.squid.S864.html Maven / Gradle / Ivy

The rules of operator precedence are complicated and can lead to errors. For this reason, parentheses should be used for clarification in complex statements. However, this does not mean that parentheses should be gratuitously added around every operation. 
This rule raises issues when && and || are used in combination, when assignment and equality or relational operators are used in together in a condition, and for other operator combinations according to the following table:

 
+, -, *, /, %
<<, >>, >>>
&
^
|
+, -, *, /, %
 
x
x
x
x
<<, >>, >>>
x
 
x
x
x
&
x
x
 
x
x
^
x
x
x
 
x
|
x
x
x
x


Noncompliant Code Example

x = a + b - c;
x = a + 1 << b;  // Noncompliant

if ( a > b || c < d || a == d) {...}
if ( a > b && c < d || a == b) {...}  // Noncompliant
if (a = f(b,c) == 1) { ... } // Noncompliant; == evaluated first

Compliant Solution

x = a + b - c;
x = (a + 1) << b;

if ( a > b || c < d || a == d) {...}
if ( (a > b && c < d) || a == b) {...}
if ( (a = f(b,c)) == 1) { ... }

See


 MISRA C:2004, 12.1 - Limited dependence should be placed on C's operator precedence rules in expressions
 MISRA C++:2008, 5-0-2 - Limited dependence should be placed on C++ operator precedence rules in expressions
 MISRA C:2012, 12.1 - The precedence of operators within expressions should be made explicit
 CERT EXP00-C - Use parentheses for precedence of operation
 CERT EXP00-CPP - Use parentheses for precedence of operation
 MITRE, CWE-783 - Operator Precedence Logic Error