// all commented code line are compilation errors #include int main() { int * const p1 = NULL; const int * p2; const int * const p3 = NULL; // p1++; (*p1)++; p2++; // (*p2)++; // p3++; // (*p3)++; return 0; } --------------------------------------------- // all commented code line are warnings of gcc and errors of g++ #include int main() { int a1; const int a2=7; int * const p1 = &a1; const int * p2 = &a1; // int * const p3 = &a2; const int * p4 = &a2; // int *p5 = &a2; return 0; }