Errors in C, C++, and other programming languages often result when a programmer fails to consider all possible data states.
Non-Compliant Code Example
This example fails to tests for conditions where a is neither b nor c. This may be the correct behavior in this case, but failure to account for all the values of a may result in logic errors if a unexpectedly assumes a different value.
...
if (a == b) {
...
}
else if (a == c) {
...
}
...
Compliant Solution
This compliant solution explicitly checks for the unexpected condition and handles it appropriately.
...
if (a == b) {
...
}
else if (a == c) {
...
}
else {
assert( (a==b) || (a == c) );
abort();
}
...
Non-Compliant Code Example
This example fails to consider all possible cases. This may be the correct behavior in this case, but failure to account for all the values of a may result in logic errors if a unexpectedly assumes a different value.
...
switch(a) {
case: 1
break;
...
}
...
Compliant Solution
This compliant solution explicitly checks for the unexpected condition and handles it appropriately.
...
switch(a) {
case: 1
break;
...
default:
assert( (a==b) || (a == c) );
abort();
}
...
References
Hatton 95 Section 2.7.2 Errors of omission and addition