const.cpp

/*
    $ clang++ const.cpp -o const && ./const
    Bus error: 10
*/

#include <stdio.h>

const char* text = "hello, world";

int main(){
    char * my_text = (char *)text;
    my_text[7] = 'X';
    printf("%s\n", my_text);
}

vtbl.cpp

/*

    $ clang++ -cc1 -fdump-record-layouts vtbl.cpp

    *** Dumping AST Record Layout
       0 | class NoVTable
       0 |   int x
       4 |   int y
         | [sizeof=8, dsize=8, align=4
         |  nvsize=8, nvalign=4]


    *** Dumping AST Record Layout
       0 | class WithVTable
       0 |   (WithVTable vtable pointer)
       0 |   (WithVTable vftable pointer)
       8 |   int x
      12 |   int y
         | [sizeof=16, dsize=16, align=8
         |  nvsize=16, nvalign=8] 

*/

class NoVTable {
public:
    int x,y;
    int addition() { return x+y; }
};

class WithVTable {
public:
    int x,y;
    virtual int addition() { return x+y; }
};

int main(){
    NoVTable nvt;
    WithVTable wvt;
    return nvt.x + wvt.x;
}