Help needed on constructors!

Modify the default constructor to that the data member is initialized to zero in the initialization list. Provide a second constructor to allow "Integer" objects to be created and initialized with a value.
In your test program, write a function that takes an Integer object as an argument, first by value and then by reference. What do you see printed from constructors and destructors when the function is called? Explain what you understand in a few statements.

Code:

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#include <iostream>
using namespace std;
//Muhammad Danish
//67
//SEECS

class R{
public:
    int danish1;
    int danish2;
    int danish3;
    R();

R(int a,int b,int c);
};

int main()
{R f;
    cout<<"Danish1="<<f.danish1;
}


R::R(int a=7,int b=9,int c=7){
danish1=a;
danish2=b;
danish3=c;
}

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So, what's the problem that you are facing?

can you differentiate b/w different types of constructors and how they are called??

Well, a default constructor is one that can be invoked with no arguments. That should have been stated somewhere in your learning material.

As to the code that you posted: I do not see the definition of an Integer class anywhere.

integer class is R.

Plus what if I want to initialize the integers by zero using default constructor.

Quote:

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Originally Posted by danishzaidi

integer class is R.

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Why does your integer class have member variables named danish1, danish2 and danish3? Oh, and why it is named R rather than Integer?

Quote:

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Originally Posted by danishzaidi

Plus what if I want to initialize the integers by zero using default constructor.

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Your current default constructor does not do that because:

• Its default arguments are integers other than 0.
• You assign to the member variables in the body of the constructor instead of using the intialiser list as per your instructions.

To get rid of plagiarism,I named it R instead of Integer and more Danish1,danish2 ,Danish 3 are integers to be initialized first by zero and other two by a value other than zero.

Code:

---

#include <iostream>
using namespace std;
//Muhammad Danish
//67
//SEECS

class R{
public:
    int danish1;
    int danish2;
    int danish3;
    int danish4;
    R();

R(int l,int w,int h);
};

int main()
{R f();
    cout<<"\n Initialised by zero using default constructor is \n"<<f().danish1;
   
R f2(10,3,6);
cout<<"\nOther by Initialised by value using Initialising list are\n"<<f2().danish2<<f().danish3<<f().danish4;
}


R::R():danish1(0){

cout<<"\nR Default constructor is called\n";
}
R::R(int l=1, int w=2, int h=3): danish2(l),danish3(w),danish4(h)
    {cout<<"\nBox contructor is invoked";
}

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dont know what to do now?

Oh, I notice that your code also has another default constructor declared. That would be an error. If you want to declare a constructor with no parameters, then your constructor that has three parameters should not have default arguments for all the parameters, otherwise it would also be a default constructor. A class can only have one default constructor.

what do u mean by default arguments????

Quote:

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Originally Posted by danishzaidi

what do u mean by default arguments????

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Look at this part:

Code:

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R::R(int l=1, int w=2, int h=3)

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You are saying that if the argument that corresponds to the parameter h is not supplied when this constructor is invoked, then h will default to having a value of 3. Likewise, if the arguments corresponding to both h and w are both not supplied, then w will have default to having a value of 2. If no arguments are supplied, then l will default to having a value of 1.

Problem is, you also declared:

Code:

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R();

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defining it as:

Code:

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R::R():danish1(0){
    cout<<"\nR Default constructor is called\n";
}

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So, if you create an object of R without supplying any arguments to its constructor, which constructor should be called? That is an ambiguity there.

Quote:

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Originally Posted by laserlight

Look at this part:

Code:

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R::R(int l=1, int w=2, int h=3)

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You are saying that if the argument that corresponds to the parameter h is not supplied when this constructor is invoked, then h will default to having a value of 3. Likewise, if the arguments corresponding to both h and w are both not supplied, then w will have default to having a value of 2. If no arguments are supplied, then l will default to having a value of 1.

Problem is, you also declared:

Code:

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R();

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defining it as:

Code:

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R::R():danish1(0){
    cout<<"\nR Default constructor is called\n";
}

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So, if you create an object of R without supplying any arguments to its constructor, which constructor should be called? That is an ambiguity there.

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Thanks mam.!