Question

In what cases will class A have at most one constructor, taking into account the constructors automatically generated by the compiler? (code using this class may be arbitrary).

Cosmo · Accepted Answer

The compiler can automatically generate two constructors - the default constructor and the copy constructor. The default constructor is only generated if there are no explicitly declared constructors in this class. A copy constructor is generated if there is an explicit declaration of this constructor. Therefore, a class can have exactly one constructor only if the copy constructor is explicitly declared.

Cosmo · Accepted Answer

struct A {
  A(const A&) {}
};

Cosmo · Answer

struct A {};

Cosmo · Answer

struct A {
  A() {}
};

Cosmo · Answer

struct A {
  explicit A(int) {}
};

Cosmo · Answer

struct A {
  void operator=(const A&) {}
};

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