Skip to main content

Dfference between delete and delete[]

There's a common myth among Visual C++ programmers that it's OK to use delete instead of delete [] to release arrays built-in types. For example,
int *p = new int[10];
delete p; // very bad; should be: delete[] p
This is totally wrong. The C++ standard specifically says that using delete to release dynamically allocated arrays of any type—including built-in types—yields undefined behavior. The fact that on some platforms apps that use delete instead of delete [] don't crash can be attributed to sheer luck: Visual C++, for example, implements both delete and delete [] for built-in types by calling free(). However, there is no guarantee that future releases of Visual C++ will adhere to this convention. Furthermore, there's no guarantees that this will work with other compilers. To conclude, using delete instead of delete[] and vice versa is a very bad programming habit that should be avoided.
Labels:

Comments

Post a Comment

Popular posts from this blog

Explain Polymorphism and Flavors of Polymorphism...

Polymorphism is the ability of different objects to react in an individual manner to the same message. This notion was imported from natural languages. For example, the verb "to close" means different things when applied to different objects. Closing a door, closing a bank account, or closing a program's window are all different actions; their exact meaning is determined by the object on which the action is performed. Most object-oriented languages implement polymorphism only in the form of virtual functions. But C++ has two more mechanisms of static (meaning: compile-time) polymorphism: Operator overloading. Applying the += operator to integers or string objects, for example, is interpreted by each of these objects in an individual manner. Obviously, the underlying implementation of += differs in every type. Yet, intuitively, we can predict what results are. Templates. A vector of integers, for example, reacts differently from a vector of string objects when it receives ...
17 comments
Read more

MFC - Microsoft Foundation Classes Design Patterns

1 Introduction This paper describes the use of object-oriented software design patterns, as presented in Design Patterns: Elements of Reusable Object-Oriented Software by Gamma et al., within the Microsoft Foundation Class Library (MFC). MFC is used for implementing applications for Microsoft Windows operating systems. Because of the size of the MFC library, a complete analysis would have been beyond the scope of this assignment. Instead, we identified various possible locations for design patterns, using the class hierachy diagram of MFC, and studied the source carefully at these locations. When we did not find a pattern where we expected one, we have documented it anyway, with examples of how the particular problem could have been solved differently, perhaps more elegantly, using design patterns. We have included a brief introduction to MFC in Section 2 , as background information. The analysis has been split into three parts, with one section for each major design pattern ca...
1 comment
Read more

Explain Mutable Object Member or data member

When a data member is declared mutable, then it is legal to assign a value to it from a const member function. The following example may demonstrate when it is needed: class Buffer { void * data; //raw data buffer to be transmitted on the net size_t size; //size of the data mutable int crc; //used to verify that no errors occurred during transmission; //a mutable variable is allowed to be modified from a const //member function. public: //... int GetCrc() const; void Transmit() const; //copmutation of crc_val should be done here }; void f() { Buffer buffer; //...fill buffer with data buffer.Transmit(); //crc can be modified here; other members may not } Class buffer uses a data buffer transmitted via communication link after it has been filled. The filling process is quite slow and repetitive, so there's no point in calculating the value of crc every time a few bytes are appended to data. On the other hand, the receiving size has to get the right crc of the data in order ...
Post a Comment
Read more