Resolve error 'there is no argument given that corresponds to required formal parameter'?

问题

I have following code where I'm getting error while compiling in C# visual Studio 2015.

class Oval:Shape
{
    private double major_axis, minor_axis;
    public Oval(double Major_Axis, double Minor_Axis)
    {
      major_axis = Major_Axis;
      minor_axis = Minor_Axis;
    } //Constructor
}
class Circle:Oval
{
    private double radius;
    public Circle(double Circle_Radius) // Getting Error on this line
    {
      radius = Circle_Radius;  
    } //constructor
}

回答1:

Fixing your bug:

The error occurs due to the lack of a parameterless constructor (or your lack of using the base() method in your constructor (just like user3185569 had said)

Fixing your code:

It clearly seems you are lacking some basics in .NET so I've decided to give a re-writing to your code with the following things in mind:

a. Conventions

There are some rules about common conventions that should apply to your code.

Members usually begin with either m or _ and then the memberName (camel casing).

Properties are usually written regularly as PropertyName and same applies to methods.

Parameters and variables are simply camel cased like parameterName

b. Access Modifiers

I don't know the use of your Oval and circle but I assume you'd want to access them outside of Oval and Circle.

I think it would be the best to reference you to here to read some more about the topic: https://msdn.microsoft.com/en-us/library/ms173121.aspx

I've re-written your code to include all those tips (and also fix your issue)

public class Oval:Shape
{       
    //Constructor
    public Oval(double majorAxis, double minorAxis)
    {
        MajorAxis=majorAxis;
        MinorAxis=minorAxis;
    } 

    protected double MajorAxis{ get; set; }     
    protected double MinorAxis{ get; set; }     
}    

public class Circle:Oval
{       
    //Constructor
    public Circle(double radius): base(radius,radius)
    {
        radius = Circle_Radius;  
    } //constructor

    public double Radius
    {
        get
        {
            return MajorAxis;
        }
        set
        {
            MajorAxis = value;
            MinorAxis = value;
        }       
    }
}

回答2:

Since Circle inherits from Oval, when you create a Circle the default constructor for Oval is called in your case. Since that constructor accepts 2 parameters, you need to explicitly call the constructor and provide them:

class Circle : Oval
{
    private double radius;
    public Circle(double Circle_Radius) : base(0, 0) // change to whatever values
    {
      radius = Circle_Radius;  
    }
}

So A Circle is an Oval, so it has major_axis and minor_axis values. You just didn't provide them as they are required values to create an Oval.

Of course you can add a default public constructor for Oval with no parameters, but that makes you create a Oval with no major_axis and minor_axis and both seems required by the only constructor in the current status of your code. So, you need to rethink how to design your classes.

回答3:

You need to update your base class constructor to the following:

class Oval:Shape
{
    private double major_axis, minor_axis;
    public Oval(double Major_Axis, double Minor_Axis)
    {
      major_axis = Major_Axis;
      minor_axis = Minor_Axis;
    } //Constructor
}
class Circle:Oval
{
    private double radius;
    public Circle(double Circle_Radius):base(12.2,12.2) // pass value to base class constructor
    {
      radius = Circle_Radius;  
    } //constructor
}~```

回答4:

class Oval : Shape   
{        
    #region Constants
    private const double dblPIE = 3.14d;
    #endregion

    #region Member_Variables
    private double m_dblMajorRad = 0.0d;
    private double m_dblMinorRad = 0.0d;
    #endregion


    #region Constructors
    /// <summary>
    /// default constructor
    /// </summary>
    public Oval()
    {

    }
    /// <summary>
    /// initializes Major Radius and Minor Radius of oval
    /// </summary>
    /// <param name="dblOvalMajorRad"></param>
    /// <param name="dblOvalMinorRad"></param>
    public Oval(double dblOvalMajorRad, double dblOvalMinorRad)
    {
        m_dblMajorRad = dblOvalMajorRad;
        m_dblMinorRad = dblOvalMinorRad;
    }
    #endregion
}

class Circle : Oval
{
    #region Constants
    private const double dblPIE = 3.14d;
    #endregion

    #region Member_Variables
    private double m_dblRadius = 0.0d;
    #endregion

    #region Constructors
    /// <summary>
    /// initializes radius
    /// </summary>
    /// <param name="dblRadius"></param>
    public Circle(double dblRadius)
    {
        m_dblRadius = dblRadius;
    }
    #endregion
}

来源：https://stackoverflow.com/questions/38758760/resolve-error-there-is-no-argument-given-that-corresponds-to-required-formal-pa

标签

oop