...
| Code Block | ||
|---|---|---|
| ||
int card = 11;
switch (card) {
/* ... */
case 11:
System.out.println("Jack");
break;
case 12:
System.out.println("Queen");
break;
case 13:
System.out.println("King");
break;
default:
System.out.println("Invalid Card");
break;
}
|
Exceptions
Applicability
Failure to include break statements can cause unexpected control flow.
MSC53-EX0: The break statement at the end of the final case in a switch statement may be omitted. By convention, this is the default label. The break statement serves to transfer control to the end of the switch block. Fall-through behavior also causes control to arrive at the end of the switch block. Consequently, control transfers to the statements following the switch block without regard to the presence or absence of the break statement. Nevertheless, the final case in a switch statement should end with a break statement in accordance with good programming style (see [Rogue 2000]).
MSC53-EX1: When multiple cases require execution of identical code, then break statements may be omitted from all cases except the last one. For example:
| Code Block | ||
|---|---|---|
| ||
int card = 11;
int value;
// Cases 11,12,13 fall through to the same case
switch (card) {
// MSC13-J:EX2: these three cases are treated identically
case 11: // break not required
case 12: // break not required
case 13:
value = 10;
break; // break required
default:
// Handle Error Condition
}
|
MSC09-EX2: When a case ends with a return or throw statement, the break statement may be omitted.
Risk Assessment
Failure to include break statements can cause unexpected control flow.
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Rule
...
Severity
...
Likelihood
...
Remediation Cost
...
Priority
...
Level
...
MSC53-JG
...
medium
...
unlikely
...
low
...
P6
...
Related Guidelines
...
CERT C Secure Coding Standard
...
MSC17-C. Finish every set of statements associated with a case label with a break statement
...
CERT C++ Secure Coding Standard
...
"CLL Switch Statements and Static Analysis" | |
CWE-484, "Omitted Break Statement in Switch" |
Bibliography
Section 14§14.11, The switch Statement | |
The Elements of Java Style, Rule 78. |
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