CODEWITHSUNDEEP
c#
hari_cheerful
hari_cheerful

Reputation: 17

Using Constructor in c# without this

I have a piece of code were i declare default constructor and parameter constructor. 

Student_APP Secondstudent = new Student_APP("2345");
            Secondstudent.score1 = 30;
            Secondstudent.score2 = 20;
            Secondstudent.score3 = 10;
            Console.WriteLine("Student Number: " + Secondstudent.studentNumber + "\nAverage: {0:F1}",
Secondstudent.CalculateAverage());
            Student_APP Thirdstudent = new Student_APP("5432", "xyz", "zxy");
            Thirdstudent.major = "Maths";
            Thirdstudent.score1 = 97;
            Thirdstudent.score2 = 56;
            Thirdstudent.score3 = 76;
            Console.WriteLine("\n\n Third student ");
            Console.WriteLine(Thirdstudent);
            Student_APP LastStudent = new Student_APP("2255", "yxx", "xyy",94,54,74,"CS");
            //LastStudent.major = "CS";
            //LastStudent.score1 = 94;
            //LastStudent.score2 = 54;
            //LastStudent.score3 = 74;

I have not used this keyword here, but i get compilation error like

Error 4 'StudentAppWithoutgetset.Student_APP' does not contain a constructor that takes 7 arguments C:\Users\hariharan.v\Desktop\Office Training\MyfirstProgCarpet\StudentApp\StudentAppWithoutgetset\StudentAppWithoutgetset\Program.cs 47 39 StudentAppWithoutgetset

Please help me.

Upvotes: 0

Views: 80

Answers (4)

Steve
Steve

Reputation: 216293

Supposing that your Student_APP class is something like this

public class Student_APP
{
    // Public properties with get/set and an automatic backing field
    public int score1 {get; set;}
    public int score2 {get; set;}
    public int score3 {get; set;}
    public string major {get; set;}

    // Internal properties
    private int _id;
    private string _surname;
    private string _name;
    public Student()
    {}
    public Student(int idnumber)
    {
        _id = idnumber;
    }
    public Student(int idnumber, string surname, string name)
    {
        _id = idnumber;
        _surname = surname;
        _name = name;
    }
}

Now you could declare and initialize an instance of this class using the Object and Collection Initializer syntax 

Student_APP s = new Student_APP(2255, "xyz", "xyz") {score1 = 94, score2=54, score3=74, major = "CS"};

Of course, if your purpose is to eliminate the public properties of the Student_APP class then you need to add an appropriace constructor that take 7 parameters as explained in other answers.

In my example above the Student_APP class has three constructors but none of them has the 7 parameters signature required by your code and thus you get the mentioned error.

Upvotes: 0

Xaero
Xaero

Reputation: 51

If I understand you correctly, everytime you do a new, e.g.

Student_APP LastStudent = new Student_APP("2255", "yxx", "xyy",94,54,74,"CS");

You are instantiating an object of Student_APP. The arguments you pass in the brackets ("2255", "yxx", "xyy",94,54,74,"CS") and the error message seems to suggest that you need to a constructor for Student_APP that takes in 7 parameters.

So in you class Student_APP you need :

public Student_APP(string firstParam, string secondParam, string thirdParam, int fourthParam, int fifthParam, int sixthParam, string seventhParam)
{
    _firstParam = firstParam;
    _secondParam = secondParam;
    //....
    _seventhParam = seventhParam;
}

Can you also give us an example of what you mean by 'this' so we can address the question with more clarity please. I think that its the root of the misunderstanding.

Upvotes: 0

user3540944
user3540944

Reputation:

the issue not related to this keyword, but it is related to the constructor it self. in your class there are no constructor that take 7 arguments so you should write it in your class before using it in the object.

public Student_APP(string p1, string p2, string p3, int p4, int p5, int p6, string p7)
{
    //...
}

Upvotes: 1

Al.exe
Al.exe

Reputation: 483

Do you have a constructor that takes 7 arguments? Try adding:

public Student_APP(string p1, string p2, string p3, int p4, int p5, int p6, string p7)
{
    //...
}

Upvotes: 1

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