When the following is compiled, it will return a different value depending on which directives are defined.
// Compile with /d:A or /d:B to see the difference
string SomeFunction()
{
#if A
return "A";
#elif B
return "B";
#else
return "C";
#endif
}
Conditional expressions are typically used to log additional information for debug builds.
void SomeFunc()
{
try
{
SomeRiskyMethod();
}
catch (ArgumentException ex)
{
#if DEBUG
log.Error("SomeFunc", ex);
#endif
HandleException(ex);
}
}