C# | Default Constructor
Last Updated :
23 Jan, 2019
If you don’t provide a constructor for your class, C# creates one by default that instantiates the object and sets member variables to the default values as listed in the Default Values Table. Constructor without any parameters is called a default constructor. In other words, this type of constructor does not take parameters. The drawback of a default constructor is that every instance of the class will be initialized to the same values and it is not possible to initialize each instance of the class to different values.
The default constructor initializes:
- All numeric fields in the class to zero.
- All string and object fields to null.
Example 1:
using System;
namespace GFG {
class multiplication
{
int a, b;
public multiplication()
{
a = 10;
b = 5;
}
public static void Main() {
multiplication obj = new multiplication();
Console.WriteLine(obj.a);
Console.WriteLine(obj.b);
Console.WriteLine( "The result of multiplication is: "
+(obj.a * obj.b));
}
}
}
|
Output:
10
5
The result of multiplication is: 50
Example 2: In this example, the class Person does not have any constructors, in which case, a default constructor is automatically provided and the fields are initialized to their default values.
using System;
public class Person
{
public int age;
public string name;
}
class TestPerson {
static void Main() {
Person pers = new Person();
Console.WriteLine( "Name: {0}, Age: {1}" , pers.name, pers.age);
}
}
|
Output:
Name: , Age: 0
Note: The output is so because a string is assigned to null by default and integers to 0.
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