CODEWITHSUNDEEP
c++constructordefault-constructor
Pranjal
Pranjal

Reputation: 508

How to initialize parameterised constructor as default constructor in c++?

How to initialize parameterised constructor as default constructor in c++? This question was asked in my exam. We were given a parametrized constructor & it worked as default constructor too.

Upvotes: 1

Views: 380

Answers (3)

dspfnder
dspfnder

Reputation: 1123

When a constructor can be invoked with no arguments, it is called a default constructor.

However, a constructor that takes arguments can be turned into a default constructor when its arguments are given default values.

For example:

class String {
public:
    String(const char∗ p = ""); // default constructor : empty string
    // ...
}

Upvotes: 0

SingerOfTheFall
SingerOfTheFall

Reputation: 29976

A default constructor, per standard (12.1/4), is:

A default constructor for a class X is a constructor of class X that can be called without an argument

So you just need to give the arguments default values:

class Foo
{
public:
    Foo(int a = 6)
    {

    }
};

int main()
{
    Foo obj;
}

Upvotes: 5

NaCl
NaCl

Reputation: 2723

class A
{
    A(int a = 0)
    {
        std::cout << a;
    }
};

Just predefine the parameters with default values.

Upvotes: 1

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