Exceptions of a C ++ rule

-- It is difficult to learn English and try to translate articles from a foreigner's blog. Start with a simple one. (Original author David)

 

Generally, you cannot modify a const type memory because it is not supported by technology. But there is a method (before the constructor runs) that allows you to do this. If 0 is passed to 80 char-sized const string parameters, the parameter becomes a variable (freeable) after it is destroyed in the destructor.

 

 # Include <iostream> </P> <p> class example <br/> {<br/> PRIVATE: <br/> const char * PTR; <br/> const bool freeable; </P> <p> Public: <br/> example (const char * optional): <br/> PTR (optional? Optional: New char [80]), <br/> freeable (optional? False: True) {}< br/> ~ Example () <br/>{< br/> If (freeable) <br/> Delete [] PTR; <br/>}</P> <p> void viewstate (char ID) <br/>{< br/> If (freeable) <br/> STD :: cout <id <"is freeable" <STD: Endl; <br/> else <br/> STD :: cout <id <"is not freeable" <STD: Endl; <br/>}< br/> }; </P> <p> int main (INT argc, char * argv []) <br/> {<br/> example S (0 ); <br/> example T ("Hello World"); <br/> S. viewstate ('s '); <br/> T. viewstate ('T'); <br/> return 0; <br/>}

We can see that S is freeable and T is not freeable.