Why is this an issue?
Assignments within sub-expressions are hard to spot and therefore make the code less readable. Ideally, sub-expressions should not have
side-effects.
Noncompliant code example
if ((str = cont.substring(pos1, pos2)).isEmpty()) { // Noncompliant
//...
Compliant solution
str = cont.substring(pos1, pos2);
if (str.isEmpty()) {
//...
Exceptions
Assignments explicitly enclosed in parentheses are ignored.
while ((run = keepRunning())) {
//...
}
Resources
- MISRA C:2004, 13.1 - Assignment operators shall not be used in expressions that yield a Boolean value
- MISRA C++:2008, 6-2-1 - Assignment operators shall not be used in sub-expressions
- MISRA C:2012, 13.4 - The result of an assignment operator should not be used
- MITRE, CWE-481 - Assigning instead of Comparing
- CERT, EXP45-C. - Do not perform assignments in selection statements
- CERT, EXP51-J. - Do not perform assignments in conditional expressions
