Introduction to Constructor and Destructor
Constructor and Destructor. The Constructor is a special function that has the same name as that of the class in which it has been defined. It is called automatically whenever a new instance is created. It is considered as a special kind of function as it is not required to be called explicitly using the object. Destructor any be defined as a special kind of method that can be revoked when the instance is deleted. The purpose of the Destructor is to free the memory that it binds with it while the instance of the class has been created. The concept of Destructor is concerned about memory management so that the resources could be utilized efficiently. In languages like C++, there exists the concept of Destructor and could be invoked automatically once the instance has been deleted while in a language like Java, the concept of Destructor does not exist. It let the program to be written in a good manner so that it could be compiled properly and can be lightweight in terms of memory consumption.
Head to Head Comparison Between Constructor and Destructor
Below is the Top 4 Comparisons Between Constructor and Destructor
Key Differences Between Constructor and Destructor
There are several differences between constructors and destructors. Below are some of the common and important differences.
- The constructor is invoked when an instance of that class is created. It doesn’t need to be called explicitly. In the case of the destructor, it invokes when the instance of any class is deleted. It is also something that comes in role automatically right after the object is deleted.
- The constructor leads to occupy the memory of the system by locating them to the resources and it is just the opposite in the case of the destructor. In destructor, the memory that was assigned to the resources is released so that it could be used by another resource.
- In order to declare the constructor, there is no need for special character. One can just create a method whose name is similar to that of the class. In the case of the destructor, the tilde sign has to be used to introduce destructor in the program.
- The constructor can be used in the high and middle-level programming language. While in the case of the destructor, it cannot be used in the high-level language. C++ is able to use the destructor but the same is not available in Java. It is due to the reason that high-level programming language had its own mechanism for memory management.
- The constructor can be found used very often in the program. It is very simple to use and reduces the complexity of the program. On the other hand, the destructor is preferred to be used when there is any need to reduce memory consumption by the program resources.
Head to Head comparison between Constructor and Destructor
| Constructor | Destructor |
| Invoked while instance creation When the instance or object of any class is created, it leads to automatically calling the constructor which will make all the statements under the constructor method to be executed. |
Invoked while instance deletion When the instance or object is deleted, the destructor invoked automatically and afterward, the statements of the destructor class are executed sequentially. |
| Occupies memory While the class is invoked, it allocates memory to all the resources that the class is going to use further. It leads to consuming the memory of the system to store the data on a permanent or temporary basis. |
Releases Memory While the destructor is invoked, it releases all the memories that the resources have been occupied. The released memory can be further located to other resources that are being used in the program. |
| Supported in mid and high-level languages The constructor is called automatically whenever an instance of that class has been created and this feature is supported by both kinds of languages: Mid and high-level programming languages. |
Support only in middle-level language The features of the destructor are only supported in a middle-level language like C++. When it comes to high-level language like Java, it doesn’t allow features like this as it has its own way to manage the memory. |
| No special character required while the declaration In order to declare the constructor, one just needs to write the name of the method that has to be the same as that of the class. There should be no special character required to declare a constructor. |
Tilde is used while a declaration In order to declare the destructor, it will be required to use a tilde. The name of the constructor has to be followed by the tilde sign and has to end with small brackets as it happens in every function. |
Conclusion
- The constructor is nothing different but just the method that has the same name as that of the class. It takes no time to get invoked once the instances are created. The object can be created in this case using the same syntax as it is used to create an object of any class. By the time the object is created, it occupies the space in the memory and brings the statement of the constructor in execution.
- The destructor is something exactly opposite to that of the constructor. It is invoked immediately after the object is deleted. Actually, when the object is deleted, it deletes all the resources that were located to it which leads to free up all the memories that were reserved by them so that the new resources could use that memory. Though there are some differences between both the concepts, they both play a vital role in programming and especially when we talk about efficient programming using the middle-level language.
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