How Does Constructor Chaining Work in C ?

Constructor Chaining in C

Constructor chaining, where one constructor calls another constructor from within its body, is a common practice in C# for initializing objects with varying parameters. C has a similar feature called delegating constructors.

C 11 and Onwards

In C 11 and later versions, delegating constructors can be used to achieve constructor chaining. The syntax is:

class Foo {
public:
  Foo(char x, int y);
  Foo(int y) : Foo('a', y) {}
};

The Foo(int y) constructor calls the Foo(char x, int y) constructor with the default value for x.

C 03 and Earlier Versions

C 03 does not support delegating constructors. However, there are two simulation methods:

• Default Parameters: Combining multiple constructors with default parameter values.

class Foo {
public:
  Foo(char x, int y = 0);  // combines constructors (char) and (char, int)
  // ...
};

• Initialization Method: Sharing common code among constructors through a private initialization method.

class Foo {
public:
  Foo(char x);
  Foo(char x, int y);
  // ...
private:
  void init(char x, int y);
};

Foo::Foo(char x)
{
  init(x, x + 7);
  // ...
}

Foo::Foo(char x, int y)
{
  init(x, y);
  // ...
}

void Foo::init(char x, int y)
{
  // ...
}

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