Editing Constructor (object-oriented programming) (section)

=== Default constructors ===
If the programmer does not supply a constructor for an instantiable class, Java compiler inserts a [[default constructor]] into your code on your behalf. This constructor is known as default constructor. You would not find it in your source code (the java file) as it would be inserted into the code during compilation and exists in .class file. The behavior of the default constructor is language dependent. It may initialize data members to zero or other same values, or it may do nothing at all. In Java, a "default constructor"  refer to a nullary constructor that is automatically generated by the compiler if no constructors have been defined for the class or in the absence of any programmer-defined constructors (e.g. in Java, the default constructor implicitly calls the [[Superclass (computer science)|superclass]]'s [[nullary]] constructor, then executes an empty body). All fields are left at their initial value of 0 (integer types), 0.0 (floating-point types), false (boolean type), or null (reference types)...

<syntaxhighlight lang="cpp">
#include <iostream>

class Student {
 public:
  Student(int a = 0, int b = 0);  // Default constructor.

  int a;
  int b;
};
</syntaxhighlight>