Code that is never executed is known as dead code. Typically, the presence of dead code indicates that a logic error has occurred as a result of changes to a program over time. Dead code is usually optimized out of a program during compilation. However, to improve readability and ensure that logic errors are resolved dead code should be identified, understood, and removed from a program.
Non-Compliant Code Example
This example, inspired by Fortify demonstrates how dead code can be introduced into a program. The second conditional statement, if (s)
may never evaluate true because it requires that s
not be assigned NULL
. However, the only path where s
can be assigned a non-NULL
value ends with a return statement.
int func(int condition) { int *s = NULL; if (condition) { s = malloc(10); if (s == NULL) { /* Handle Error */ } /* insert data into s */ return 0; } /* ... */ if (s) { /* This code is never reached */ } }