Effective C + +. Performance of default parameters in the Notoginseng virtual function

#include <iostream>#include<cstdlib>using namespacestd;classPen { Public:    Virtual voidWriteintcolor =0) {cout<<"write with color:"<<color<<Endl; }};classPencil: Publicpen{ Public:    voidWriteintcolor = -) {cout<<"write with color:"<<color<<Endl; }};intMain () {Pen* p =NewPencil (); P-write (); return 0;}

Output:

Write with color:0

That is, the virtual function, which executes the function is determined by the runtime, but its default parameters are statically determined, which type of pointer is used to use which set of default parameters.

Therefore, it is best not to have default parameters in the virtual function

Effective C + +. Performance of default parameters in the Notoginseng virtual function