What is a constructor initializer list and when we use constructor initializer

What is a constructor initializer list and when we use
constructor initializer list?

Question Posted / vasudevan

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What is a constructor initializer list and when we use constructor initializer list? ..

Answer / deep

There is couple special case when you need mandatory
constructor initialization list.

a. To initialise a const
b. To initialise a reference

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What is a constructor initializer list and when we use constructor initializer list? ..

Answer / sachin mahajan

Main purpose of the contstuctor is to initialize the data
members with some valid values. This can be done in two ways
class MyClass{
int I,J;
public:
MyClass(int i,int j )
{
I=i;J=j;
}
};
Above the most common way to initialize data members .Other
way is
MyClass(int i,int j):I(i),J(j)
{
}
i(0),j(0) is the initialization list.

Constuctor Initialization list is used when we want to pass
some data to the constructor the parent class.
Below is the example:
class Parent
{
int I;
public:
Parent(int i)
{
I=i;
}
};
class Child:public Parent
{
int J;
public:
Child(int i,int j):Parent(i),J(j)
{

}

};

main()
{
Child c(1,2);
//now 1 is passed to parent and 2 is passed to Child
}