Why Should C++ Programmers Minimize Use of ‘new’?

C++ programmers should minimize the use of the new operator for managing the memory properly in C++ programming and to avoid memory-related issues. In this article, we will discuss why C++ programmers should minimize the use of the new operator, the common reasons or issues, and the alternatives to new in C++.

Table of Contents:

• Understanding new in C++
• Reasons to Minimize the Use of new in C++
  • Memory Leaks
  • Dangling Pointers
  • Double Deletion
  • Exception Safety Issues
  • Manual Memory Management Complexity
• Alternatives to new in C++
  • Smart Pointers
  • Containers from the Standard Library
  • Automatic Storage Duration (Stack Allocation)
  • Placement New
• Conclusion

Understanding new Operator in C++

The new operator in C++ is used for dynamic memory allocation, which allows the objects and variables to be allocated on the heap at runtime. It provides you the flexibility for memory allocation but also comes with disadvantages such as memory leaks, manual deallocation requirements, and exception safety concerns. So, due to these disadvantages, programmers should minimize the use of the new operator in C++.

Reasons to Minimize the Use of new in C++

Below are a few problems that can arise when you use the new operator directly in C++:

1. Memory Leaks

When you use the new operator directly without calling the delete operator after the new in C++, then it will lead to memory leaks. You know that memory leaks can cause excessive memory usage and can also degrade the performance of the system.

Example:

Output:

The code shows how the memory is allocated in memoryleak() for an integer using the new operator but is not freed, and the function is called in a loop five times, which results in multiple memory allocations and causes a memory leak in a C++ program by using the new operator directly.

2. Dangling Pointers

A dangling pointer in your program occurs when the memory allocated to the pointer is deleted or does not exist, but the pointer is still used in the program. So, accessing that pointer will lead to undefined behavior, crashes, or data corruption in the program.

Example:

Output:

The code shows how the user is allocating memory to a pointer with the value of 10 using the new operator, and then deletes it using the delete after the value is printed. Trying to access this pointer will lead to a dangling pointer. 

3. Double Deletion

When you use the new operator for allocating the memory to a pointer, and if the delete operator is used twice in the program on the same pointer, it will lead to undefined behavior or memory crashes. 

Example:

Output:

The code shows that the double deletion occurs in the C++ program as the delete operator is called twice on the same pointer, which is called using the new operator, and it is causing undefined behavior, and accessing this pointer after deleting it can cause crashes and unexpected results.

4. Exception Safety Issues

When you are using the new operator in your program, and an exception occurs after the new but before the delete operator, then the memory will leak.

Example:

Output:

The code shows how an exception occurs after a memory is allocated using the ‘new’ operator but before deleting that memory using the ‘delete’ operator, which is causing the memory leaks.

5. Manual Memory Management Complexity

Keeping track of all the memory that is allocated is a very complex and difficult task and can lead to potential errors. So, using the new operator in big projects whose memory may need to be managed manually is not a good practice.

Example:

Output:

Alternatives to new in C++

There are a few alternatives to new that you can use for managing memory, safety, and efficiency. 

1. Smart Pointers 

You can use the smart pointers instead of using the new operator, as they are the objects that manage the memory of the dynamically allocated resources automatically.

Example:

Output:

The code shows how a smart pointer, std::unique_ptr, is used for managing dynamic memory in C++ instead of the new operator and also to minimize issues such as dangling pointers and manual memory management. 

2. Containers from the Standard Library

The C++ standard library provides you with several different container classes that can manage the memory automatically and reduce the need to use the new and delete operators. Also, these containers provide a more secure and efficient way to store and manipulate the collection of objects in C++.

Example:

Output:

The code shows how the container class std::vector is used instead of the new operator to manage the memory automatically, as it initializes the vector with values(1, 2, 3), adds two more values (4 and 5), and then iterates over the vector to print the elements. 

3. Automatic Storage Duration (Stack Allocation)

You should use stack allocation instead of dynamic allocation because the stack-allocated objects are automatically destroyed when they go out of scope and reduce memory management complexity.

Example:

Output:

The code shows how the stack allocation is used to declare an integer a and b with the values 10 and 20.5 and to print the values, instead of dynamic allocation to minimize the risk of memory management complexities.

4. Placement New

You must use the placement new operator instead of the new operator where you need to create the objects in a pre-allocated memory buffer. It helps you to customize memory management and optimization.

Example:

Output:

The code shows how the placement new operator is used to create a MyObject instance in an already allocated buffer instead of the new operator for better memory management. Also, it allocates memory using the std::malloc with a value of 42, prints it, and then frees the memory.

Conclusion

As we have discussed above in this blog, the new operator in C++ allows for dynamic memory allocation, but directly using it in our C++ programs can lead to many different errors and issues. So, to minimize these errors and issues, C++ programmers should minimize the use of the new operator and instead use the other discussed alternatives. By using these alternatives, you can easily create efficient C++ applications with reduced memory issues.

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