I just can't get it. What is wrong in this?

Question

Please see the error and help me. Its showing error. I just can't understand where is the problem?? I have resolved all the errors that could be solved but still I am stuck. I know this is a vey simple question and its very frustrating.

The question is: Create a class calculate that uses two separate functions:-a function to multiply two float numbers and another to divide two float numbers using the concept of inline function. Also, create a method to print the result on the screen.

#include <iostream>
using namespace std;

class calculate
{
    float a,b;

    public:
    float multiply(float a, float b);
    float divide(float a, float b);
};

inline float calculate :: multiply(float a, float b)
{
     return a*b;
}

inline float calculate :: divide(float a, float b)
{
    return a/b;
}

int main()
{
    float a,b;
    cout<<"Enter two float numbers: ";
    cin>>a>>b;

    calculate obj (a,b);
    cout<<"Multiplication: "<<obj.multiply(a,b)<<endl;
    cout<<"Division: "<<obj.divide(a,b)<<endl;

    return 0;
}

Answer 1

Compiling your program yields the compiler error:

error: no matching function for call to 'calculate::calculate(float&, float&)'
   29 |     calculate obj (a,b);

This is telling you that on the line where you construct a calculate object named obj by invoking a constructor that takes two float arguments, no such constructor in the class calculate exists.

Looking at the class, you did not define any such constructor. This is easily fixed:

class calculate
{
    float a, b;

public:
    calculate(float a, float b);
    float multiply(float a, float b);
    float divide(float a, float b);
};

calculate::calculate(float a, float b)
    : a(a)
    , b(b)
{
}

Now your class can be constructed as you wanted:

calculate obj(a, b);

Answer 2

#include <iostream>
using namespace std;

class calculate
{
    float a, b;

public:
    calculate(float a, float b);
    float multiply(float a, float b);
    float divide(float a, float b);
};
calculate::calculate(float a, float b)
    : a(a)
    , b(b)
{
}

inline float calculate::multiply(float a, float b)
{
    return a * b;
}

inline float calculate::divide(float a, float b)
{
    return a / b;
}

int main()
{
    float a, b;
    cout << "Enter two float numbers: ";
    cin >> a >> b;

    calculate obj(a, b);
    cout << "Multiplication: " << obj.multiply(a, b) << endl;
    cout << "Division: " << obj.divide(a, b) << endl;

    return 0;
}

Credit:-Paddy(https://stackoverflow.com/users/1553090/paddy)