Complex sentence: Some functions perform destructive operations before calling the runtime-constraint handler; for example, strcat_s sets the destination to the empty string, which can make it difficult to recover from error conditions in case the program installs a runtime-constraint handler that returns.
Split into simpler sentences: Some functions perform destructive operations before calling the runtime-constraint handler. For example, strcat_s sets the destination to the empty string, which can make it difficult to recover from error conditions in the case where the program installs a runtime-constraint handler that returns.