Re: How do I add 3 objects to array in C# - C# Discussion Boards

C# timesheet business logic question

20-Apr-15 6:34

If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson

Member 1162043719-Apr-15 12:21

Member 11620437

19-Apr-15 12:21

So I have a web application for a time log management system. I have it to where you can create a timelog if you are an employee for the hours you have previously worked. I cannot figure out how to enable employees from entering in future work hours on the timelog entry and need some help please!

Re: C# timesheet business logic question

Sascha Lefèvre19-Apr-15 12:25

How do I add 3 objects to array in C#

19-Apr-15 12:25

Member 11620437 wrote:
I cannot figure out how to

You need to provide technical details. How are we supposed to figure it out when knowing nothing about it beyond it's intended purpose?

Quote:[^]
- Put yourself in the shoes of someone trying to answer this. Can you really imagine anyone can? What are you expecting the answer to this could be?
- How does it not work? What did you do? What were you expecting, and what happened instead?
- Ask yourself: is there enough information for anybody who’s not you to figure out what the problem is?
- Notice how asking a question that is too vague will only get you more questions in return.

If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson

modified 19-Apr-15 18:45pm.

Aindriu Mac Giolla Eoin19-Apr-15 8:27

19-Apr-15 8:27

Hi,

How can I add 3 objects to an array in C# ? I created 3 objects of a class and I want those three objects in an array in another class but I get the syntax wrong.

here in the main method I created 3 objects from Class student

static void Main(string[] args)
        {

         //  Create 3 students
            Student student1 = new Student

            {
                FirstName = "John",
                LastName = "Wayne",
                BirthDate = "26/05/1907"

            };

            Student student2 = new Student
            {
                FirstName = "Craig",
                LastName = "Playstead",
                BirthDate ="01/01/1967"
            };

            Student student3 = new Student
            {
                FirstName = "Paula",
                LastName = "Smith",
                BirthDate = "01/12/1977"
            };

In another class I want to create an array and put the 3 student objects into it, how do I do that ? So far I only created an array[3]

Public class Course
        {
            private string courseName;

            public string CourseName
            {
                get { return courseName; }
                set { courseName = value; }
            }


            Student[] studentarray = new Student[3];

modified 19-Apr-15 14:35pm.

Sascha Lefèvre19-Apr-15 8:31

19-Apr-15 8:31

Very easy:

Student[] studentarray = new Student[3];

studentarray[0] = student1;
studentarray[1] = student2;
studentarray[2] = student3;

If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson

Aindriu Mac Giolla Eoin19-Apr-15 8:33

19-Apr-15 8:33

thanks, i got the syntax mixed up !

**edit., i get lots of errors when I try this

Error 1 Array size cannot be specified in a variable declaration (try initializing with a 'new' expression)

Sascha Lefèvre19-Apr-15 8:38

19-Apr-15 8:38

You're welcome!

Consider using a generic List instead of an array (if you don't use an array on purpose for some reason). It's way more flexible, e.g. allows dynamic growth in contrast to an array. Would look like this:

List<Student> students = new List<Student>();

students.Add(student1);
students.Add(student2);
students.Add(student3);

(put a using System.Collections.Generic; at the top of your source file.)

If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson

Aindriu Mac Giolla Eoin19-Apr-15 8:44

19-Apr-15 8:44

its not letting me add the objects to the array created.

studentarray[0] = student1;
Error: Array size cannot be specified in a variable declaration (try initializing with a 'new' expression)

I created the 3 objects (of another class called Student) in the main method, I don't know if I can add the three objects from there ?

PIEBALDconsult19-Apr-15 9:01

PIEBALDconsult

19-Apr-15 9:01

Please edit your question to include the code as you have it now, and the exact error message you are receiving.

Sascha Lefèvre19-Apr-15 9:03

19-Apr-15 9:03

I assume you've put the assignment into the class-scope, like so (15th line or so):

Public class Course
{
    private string courseName;
 
    public string CourseName
    {
        get { return courseName; }
        set { courseName = value; }
    }

    // this would be ok, because it's a "declaration" like "private string courseName;" above
    Student[] studentarray = new Student[3]; 

    // this isn't a declaration and can't exist directly in the class scope:
    studentarray[0] = student1;

    // instead theoretically something like this (within a methods scope):
    public void SomeMethod()
    {
        studentarray[0] = student1;
        // "theoretically" because "student1" isn't known here
    }
    
    // makes a tiny bit more sense:
    public void SetStudent0(Student student)
    {
        studentarray[0] = student;
        // only a tiny bit because this method would have the fixed purpose
        // of assigning to array index 0
    }
    // you would call it outside of this class like so: someCourse.SetStudent0(student1);

    // some more sense:
    public void SetStudent(Student student, int index)
    {
        studentarray[index] = student;
        // only some more sense because from outside this class you don't know which
        // array indices would be valid
    }
    // you would call it outside of this class like so: someCourse.SetStudent(student1, 0);

    // even more sense:
    private int ArrayCursor = 0;
    public void AddStudent(Student student)
    {
        studentarray[ArrayCursor] = student;
        ArrayCursor++;
        // will only work as long as there's enough space in the array
    }
    // you would call it outside of this class like so: someCourse.AddStudent(student1);

    // best with a generic list:
    private List<Student> Students = new List<Student>();
    public void AddStudent(Student student)
    {
        Students.Add(student);
    }
}

If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson

Aindriu Mac Giolla Eoin19-Apr-15 9:13

19-Apr-15 9:13

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;

namespace Assignment5
{
class Program
{
static void Main(string[] args)
{

// Create 3 students
Student student1 = new Student

{
FirstName = "John",
LastName = "Wayne",
BirthDate = "26/05/1907"

};

Student student2 = new Student
{
FirstName = "Craig",
LastName = "Playstead",
BirthDate ="01/01/1967"
};

Student student3 = new Student
{
FirstName = "Paula",
LastName = "Smith",
BirthDate = "01/12/1977"
};

// Create Teacher
Teacher teacher1 = new Teacher
{
TeacherfirstName = "Paul",

};

// Create course object
Course course = new Course();
course.CourseName = "Programming with C#.";

// Create degree object
Degree degree = new Degree();
degree.DegreeName = "Bachelor of Science Degree";

// Create Program object
UProgram uprogram = new UProgram();
uprogram.ProgramName = "Information Technology";

// count = GetActiveInstances(typeof(Student));

Console.WriteLine("The {0} program contains the {1} ", uprogram.ProgramName, degree.DegreeName);
Console.WriteLine("The {0} contains the course {1} ",degree.DegreeName, course.CourseName );
// Console.WriteLine("The {0} course contains students(s)" count);
Console.WriteLine("Count" + Student.count);

Console.Read();
}

public class Student
{
public static int count = 0;
public Student()
{
// Thread safe since this is a static property
Interlocked.Increment(ref count);
}

// use properties!
private string firstName;

// Get Set for FirstName
public string FirstName

{
get { return firstName; }
set { firstName = value; }
}

private string lastName;
// Get Set for LastName
public string LastName
{
get { return lastName; }
set { lastName = value; }
}

private string birthDate;
// Get Set for BirthDate
public string BirthDate
{
get { return birthDate; }
set { birthDate = value; }
}

}

public class Teacher
{

private string teacherfirstName;

public string TeacherfirstName
{
get { return teacherfirstName; }
set { teacherfirstName = value; }
}
// string teacherlastName;
// string teacheroffice;

}

public class UProgram
{
private string programName;

public string ProgramName
{
get { return programName; }
set { programName = value; }
}
// string degreeOffered;
// string department;

}

public class Degree
{
private string courseName;

public string DegreeName
{
get { return courseName; }
set { courseName = value; }
}

}

public class Course
{
private string courseName;

public string CourseName
{
get { return courseName; }
set { courseName = value; }
}

Student[] studentarray = new Student[3];

studentarray[0] = student1;

// studentarray[1] = student2;
// studentarray[2] = student3;

Teacher[] teacherarray = new Teacher[3];
}

}
}

Sascha Lefèvre19-Apr-15 9:16

19-Apr-15 9:16

Yes - it's what I assumed it my last reply Smile | :)

You inserted the assignment to array-index 0 directly within class-scope. It has to happen in a method (or, theoretically, in the constructor).

If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson

Aindriu Mac Giolla Eoin19-Apr-15 9:24

19-Apr-15 9:24

thanks for the post ! I will create a method and increment through the 3 students and add them, i will call the method outside the class

Sascha Lefèvre19-Apr-15 9:27

19-Apr-15 9:27

tá fáilte romhat Smile | :)

If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson

Aindriu Mac Giolla Eoin19-Apr-15 9:32