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C++ Operator Overloading | Find output programs | Set 4

This section contains the C++ find output programs with their explanations on C++ Operator Overloading (set 4).
Submitted by Nidhi, on July 02, 2020

Program 1:

#include <iostream>
using namespace std;

class Test {
    float A;

public:
    Test(float a)
    {
        A = a;
    }

    void operator++(int)
    {
        A++;
    }

    void print()
    {
        cout << A << endl;
    }
};

int main()
{
    Test T1(10.5F);
    T1++;
    T1.print();
    return 0;
}

Output:

11.5

Explanation:

Here, we create a Test class that contains data member A of float type. And, we defined a default constructor and member function print() to print the value of A, also defined member function to overload post-increment operator by passing dummy argument int. Without the dummy argument, the function will be overloaded for the pre-increment operator.

Program 2:

#include <iostream>
using namespace std;

class Test {
    float A;

public:
    Test()
    {
        A = 0.0F;
    }
    Test(float a)
    {
        A = a;
    }

    void operator++(float)
    {
        A++;
    }

    void print()
    {
        cout << A << endl;
    }
};

int main()
{
    Test T1(10.5F);
    T1++;
    T1.print();
    return 0;
}

Output:

main.cpp:17:26: error: postfix ‘void Test::operator++(float)’ 
must take ‘int’ as its argument
     void operator++(float)
                          ^
main.cpp: In function ‘int main()’:
main.cpp:31:7: error: no ‘operator++(int)’ declared for 
postfix ‘++’ [-fpermissive]
     T1++;
     ~~^~

Explanation:

It will generate compilation error, because, to overload post-increment operator, we need to pass int as a dummy argument. Otherwise, it will generate an error.

Program 3:

#include <iostream>
using namespace std;

class Test {
    float A;

public:
    Test(float a)
    {
        A = a;
    }

    void operator<<()
    {
        cout << A << endl;
    }
};

int main()
{
    Test T1(10.5F);
    T1 << ;
    return 0;
}

Output:

main.cpp:13:21: error: ‘void Test::operator<<()’ 
must take exactly one argument
     void operator<<()
                     ^
main.cpp: In function ‘int main()’:
main.cpp:22:11: error: expected primary-expression before ‘;’ token
     T1 << ;
           ^

Explanation:

It will generate compilation error, because, to overload the "<<" operator, we need to pass exactly one argument to the overloaded function.

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