C++ Interview Question and Answers
| 116. |
What is an adaptor class or Wrapper class? |
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A class that has no functionality of its own. Its member functions hide the use of a third party software component or an object with the non-compatible interface or a non-objectoriented implementation. |
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| 117. |
What is a Null object? |
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It is an object of some class whose purpose is to indicate that a real object of that class does not exist. One common use for a null object is a return value from a member function that is supposed to return an object with some specified properties but cannot find such an object. |
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| 118. |
What is class invariant? |
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- A class invariant is a condition that defines all valid states for an object.
- It is a logical condition to ensure the correct working of a class.
- Class invariants must hold when an object is created, and they must be preserved under all operations of the class.
- In particular all class invariants are both preconditions and post-conditions for all operations or member functions of the class.
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| 119. |
What is the difference between the message and method? |
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Message : Objects communicate by sending messages to each other.A message is sent to invoke a method.
Method : Provides response to a message and it is an implementation of an operation. |
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| 120. |
Is it possible to use a new for the reallocation of pointers? |
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The reallocation of pointers cannot be done by using new. It can be done by using the realloc() operator. |
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