Empty classes of C + + and multiple inheritance occupy memory space

1. Output in code results

#include <iostream>using namespacestd;classA {};classA2 {};classD | PublicA {};classE | PublicA PublicA2 {};classB | Public VirtualB {};intMain () {cout<<sizeof(A) <<Endl; cout<<sizeof(B) <<Endl; cout<<sizeof(C) <<Endl; cout<<sizeof(D) <<Endl; return 0;}

2. Results

1114

3, analysis

Empty class occupies an inner space of 1

Empty class space for single or multiple-inheritance empty classes is still 1

However, virtual inheritance involves virtual pointers, the pointer size is 4, so the empty class occupies a space of 4 after virtual inheritance

Empty classes of C + + and multiple inheritance occupy memory space