What’s the difference between a pointer and a reference? They both seem to do the same thing—point to another variable. Well, there are some important differences. A pointer can be aliased, whereas a reference cannot. Also, a pointer can be NULL, whereas a reference cannot. Let’s take a closer look at these two data types.
What is Pointer?
- Pointers are variables that store the address of another variable. They are often used to store the address of an array or structure or to pass the address of a variable to a function.
- Pointers can also be used to dynamically allocate memory. Pointer arithmetic is also possible in C and C++, which allows pointer variables to be incremented or decremented. When a pointer is dereferenced, the value of the pointed-to variable is obtained.
- Pointers are a powerful feature in C and C++, but they can also be dangerous if they are not used correctly. Pointers can be initialized to point to NULL, which indicates that they are not pointing to any valid data. It is important to check whether a pointer is NULL before dereferencing it, as this can lead to undefined behavior.
What is Reference?
Reference is a value that refers to another value. In other words, a reference is like an alias for another value. Reference is supported in C++ and Python. In C++, references are declared with the & operator. For example, int& x = y; declares x as a reference to y. In Python, references are declared with the keyword global.
- For example, global x = y declares x as a reference to y. When a reference is used, the value it refers to is accessed. For example, if x is a reference to y, then x will access the value of y. Reference variables must be initialized when they are declared. You cannot declare a reference variable and then later assign it a value. Also, you cannot change what a reference variable refers to once it has been initialized.
- So, if you have a reference variable that initially refers to one value, it will always refer to that value (unless it goes out of scope). Reference variables are often used for function parameters and return values. This allows you to pass large objects by Reference variables are often used for function parameters and return values.
- Reference parameters allow you to pass large objects by Reference without making copies. Return by Reference allows a function to return an object without making copies. References can also be used with smart pointers. Smart pointers are objects that act like pointers but also handle memory management tasks automatically.
By using references with smart pointers, you can avoid some of the problems associated with raw pointers while still enjoying the benefits of Reference variables are often used for function parameters and return values allowing you to pass large objects by Reference without making copies. Return by Reference allows a function to return an object without making copies of automatic memory management support from smart pointers!
Difference between Pointer and Reference
Pointers and references are two important language constructs in C++ that allow you to manipulate data stored in memory.
- Pointers are variables that store the address of another variable, while references are variables that store an alias for another variable.
- Pointers can be reassigned to point to different data, while references always refer to the same data. Pointers can be NULL, while references cannot.
- Pointers can be incremented and decremented, while references cannot. Lastly, pointers can be dereferenced using the * operator to access the data they point to, while references cannot.
These are the main differences between pointers and references in C++. Understanding how these two language constructs work is essential for programming in C++.
Conclusion
In the world of programming, pointers and references are two important concepts to understand. References are variables that hold the memory address of another variable. Pointers, on the other hand, are variables that store the memory address of a reference variable. When you pass a pointer to a function, the function can modify the value stored in the pointer, but it cannot access or modify the data pointed to by the reference variable. References are often used when passing large objects around functions because they take up less space than pointers. If you want to learn more about how pointers and references work in C++, check out our tutorial on the subject.
