c# generics - need help

Hello,

The statements III and IV are true. The statement 1 is not true as it explains incomplete behaviour.

You can try using following examples:

class genericClass where T: class, IComparable

{

public void somemethod(T t)

{

Console.Write(t.ToString());

Console.Read();

}

class Employee : IComparable

{

public int Salary { get; set; }

public string Name { get; set; }

public int CompareTo(object other)

{

Employee emp = (Employee)other;

// Alphabetic sort if salary is equal. [A to Z]

if (this.Salary == emp.Salary)

{

return this.Name.CompareTo(emp.Name);

}

// Default to salary sort. [High to low]

return emp.Salary.CompareTo(this.Salary);

}

public override string ToString()

{

// String representation.

return this.Salary.ToString() + "," + this.Name;

}

class EmployeeWithoutIComparable

{

public int Salary { get; set; }

public string Name { get; set; }

}

struct EmployeeStruct : IComparable

{

public int Salary { get; set; }

public string Name { get; set; }

public int CompareTo(object other)

{

Employee emp = (Employee)other;

// Alphabetic sort if salary is equal. [A to Z]

if (this.Salary == emp.Salary)

{

return this.Name.CompareTo(emp.Name);

}

// Default to salary sort. [High to low]

return emp.Salary.CompareTo(this.Salary);

}

public override string ToString()

{

// String representation.

return this.Salary.ToString() + "," + this.Name;

}

}
//Calling from Main without implementing IComparable
genericClass g1 = new genericClass();
Compilation error : 'Corner.EmployeeWithoutIComparable' cannot be used as type parameter 'T' in the generic type or method 'Corner.genericClass'. There is no implicit reference conversion from 'Corner.EmployeeWithoutIComparable' to 'System.IComparable'.

//Calling from Main with struct and implementing IComparable
genericClass g1 = new genericClass();
Compilation error : The type 'Corner.EmployeeStruct' must be a reference type in order to use it as parameter 'T' in the generic type or method 'Corner.genericClass'

//Calling from Main with class and implementing IComparable

Employee objE = new Employee();

objE.Name = "Test1";

objE.Salary = 10000;

genericClass g1 = new genericClass();

g1.somemethod(objE);

This is running fine.

Hope it makes clear to you.

Thanks

1 Reply

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Dhirendra Misra12y ago
Hello,

The statements III and IV are true. The statement 1 is not true as it explains incomplete behaviour.

You can try using following examples:
class genericClass where T: class, IComparable
{
public void somemethod(T t)
{
Console.Write(t.ToString());
Console.Read();
}
}

class Employee : IComparable
{
public int Salary { get; set; }
public string Name { get; set; }

public int CompareTo(object other)
{
Employee emp = (Employee)other;
// Alphabetic sort if salary is equal. [A to Z]
if (this.Salary == emp.Salary)
{
return this.Name.CompareTo(emp.Name);
}
// Default to salary sort. [High to low]
return emp.Salary.CompareTo(this.Salary);
}

public override string ToString()
{
// String representation.
return this.Salary.ToString() + "," + this.Name;
}
}

class EmployeeWithoutIComparable
{
public int Salary { get; set; }
public string Name { get; set; }
}

struct EmployeeStruct : IComparable
{
public int Salary { get; set; }
public string Name { get; set; }

public int CompareTo(object other)
{
Employee emp = (Employee)other;
// Alphabetic sort if salary is equal. [A to Z]
if (this.Salary == emp.Salary)
{
return this.Name.CompareTo(emp.Name);
}
// Default to salary sort. [High to low]
return emp.Salary.CompareTo(this.Salary);
}

public override string ToString()
{
// String representation.
return this.Salary.ToString() + "," + this.Name;
}
}
//Calling from Main without implementing IComparable
genericClass g1 = new genericClass();
Compilation error : 'Corner.EmployeeWithoutIComparable' cannot be used as type parameter 'T' in the generic type or method 'Corner.genericClass'. There is no implicit reference conversion from 'Corner.EmployeeWithoutIComparable' to 'System.IComparable'.

//Calling from Main with struct and implementing IComparable
genericClass g1 = new genericClass();
Compilation error : The type 'Corner.EmployeeStruct' must be a reference type in order to use it as parameter 'T' in the generic type or method 'Corner.genericClass'

//Calling from Main with class and implementing IComparable
Employee objE = new Employee();
objE.Name = "Test1";
objE.Salary = 10000;

genericClass g1 = new genericClass();
g1.somemethod(objE);
This is running fine.

Hope it makes clear to you.

Thanks