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Case 1:
I am trying this
MessageBox m = new MessageBox();
And got compilation error
'System.Windows.Forms.MessageBox' has no constructors defined
Case 2:
Then, I have made a class without constructor
class myClass
{
}
and tried myClass my = new myClass(); This time I found no error.
Now, my question:
Since, both are classes and every class have default constructor, then
362
No default constructor is created for a class that has any constant or reference type members. A constructor of a class A is trivial if all the following are true: It is implicitly defined. A has no virtual functions and no virtual base classes.
In c#, if we create a constructor without any parameters, we will call it a default constructor. Every instance of the class will be initialized without any parameter values. Following is the example of defining the default constructor in the c# programming language.
A default constructor is a constructor that either has no parameters, or if it has parameters, all the parameters have default values. If no user-defined constructor exists for a class A and one is needed, the compiler implicitly declares a default parameterless constructor A::A() .
Although the CLR allows it, C# does not allow structs to have a default parameter less constructor. The reason is that, for a value type, compilers by default neither generate a default constructor, nor do they generate a call to the default constructor.
The constructor may be private or protected in order to forbid direct instantiation. Use the static factory method instead. There is a static method Show in the MessageBox class.
Archil is right, too. If theres a explicit constructor defined, the implicit default constructor is not created anymore.
And regarding x0ns comments: Yes, it's also impossible to instantiate static classes. Don't use static classes, thats poor design (there are exceptions).
121
In c#, evey class automatically has default constructor if NONE is defined. MessageBox defines other constructors, so it does not automatically have default constructor
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