C6259
Note
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warning C6259: labeled code is unreachable: (<expression> & <constant>) in switch-expr cannot evaluate to <case-label>
This warning indicates unreachable code caused by the result of a bitwise-AND (&) comparison in a switch expression. The case statement that matches the constant in the switch expression is only reachable; all other case statements are not reachable.
Example
The following sample code generates this warning because the expression switch``(rand() & 3) cannot evaluate to case label (case 4):
#include <stdlib.h>
void f()
{
switch (rand () & 3) {
case 3:
/* Reachable */
break;
case 4:
/* Not reachable */
break;
default:
break;
}
}
To correct this warning, remove the unreachable code or verify that the constant used in the case statement is correct. The following code removes the unreachable case statement:
#include <stdlib.h>
void f()
{
switch (rand () & 3) {
case 3:
/* Reachable */
break;
default:
break;
}
}