C++:CopyConstructors

lastmod 2025-02-14created 2017-01-164 edits

Copy constructors in C++.

Example

You can create an example like the one below.

#include <iostream>
using namespace std;

struct A
{
    int * ptr;
    A(int a) { ptr = new int(a); }
    ~A() { delete ptr; }
};

int main()
{
    A a1(100);
    A a2 = a1;

    return 0;
}

In the case above, a1.ptr and a2.ptr point to the same Pointer (shallow copy), so the program crashes when the destructor is called twice.

When run, it crashes as shown below.

$ ./a.out
a.out(62678,0x7fffc1a733c0) malloc: *** error for object 0x7fb914c02790: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
Abort trap: 6

See also

• C++:DefaultConstructors: an explanation of default constructors.
• C++:virtual
• Korean: 얕은 복사 (Shwallow Copy)
• Korean: 깊은복사 (Deep Copy)

Favorite site

• C++: Copy Constructor