Why this doesn't accept a parameter of a class-type? What can I read about it? Here is my useless code
using System;
public class Class1
{
public int a = 5;
}
public class Class2
{
private readonly int num;
Class1 obj2 = new Class1();
public Class2(Class1 obj)
{
num = obj.a;
}
public Class2(string l) : this (Class1 obj2)
{
}
}
Your constructor takes an instance of Class1, so you should use:
public Class2(string l) : this (new Class1())
{
}
You will probably also want to assign the constructor argument to your obj2 member instead of creating a new one:
public class Class2
{
private readonly int num;
Class1 obj2;
public Class2(Class1 obj)
{
this.obj2 = obj;
num = obj.a;
}
public Class2(string l) : this (new Class1()) { }
}
obj parameter in the other constructor so it won't get collected.First let's look at:
public Class2(string l) : this (Class1 obj2) {...}
Firstly, you don't include the type in an invocation, so it would be:
public Class2(string l) : this (obj2) {...}
But: obj2 is not valid at that point: the constructor (which kinda includes the field initializer) has not run yet, so fields on this (such as this.obj) are not legal at that location. as Lee notes: just pass in a null or new instance.
int i = Math.Min(int 1, int 3) - you call int i = Math.Min(1,3)A class can inherit from another class. The this keyword refers to an instance of a class and instances do not exist at "develop-time"
You cannot use that string and pass it to another contructor that takes Class1 as argument. You need to create a Class1 object. But since that needs an int i would not use a constructor that takes string but int. Otherwise you would need to use int.Parse which could throw an excption and exceptional constructors are not good practise(when they could be avoided).
public Class2(int i)
: this(new Class1() { a=i })
{
}
public Class2(string l) : this (obj2)