Pointer vs. Reference: What's the Difference?
Edited by Aimie Carlson || By Janet White || Published on February 11, 2024
A pointer is a variable that holds a memory address, while a reference is an alias for an already existing variable.
Key Differences
A pointer in programming languages like C++ is a variable that stores the address of another variable. It can be reassigned to point to different addresses. A reference, on the other hand, is an alias for another variable and once set, it cannot be made to reference another variable.
Pointers can be assigned null, meaning they point to nothing. This feature makes them useful for checking if they have valid data. References must always refer to an object; they cannot be null. This ensures that a reference always points to a valid memory location.
With pointers, direct manipulation of memory addresses is possible. This includes arithmetic operations on addresses. References do not allow such direct interaction with memory addresses, making them safer but less flexible.
A pointer requires explicit dereferencing to access the target object’s value. References implicitly refer to the value of the object they are referencing, making them easier to use but hiding the underlying complexity.
Pointers are often used in complex data structures, dynamic memory allocation, and low-level system programming due to their flexibility. References are used when a variable must be passed by reference to functions or when an alias for a variable is needed, ensuring more straightforward and safer code.
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Comparison Chart
Nullability
Can be null
Cannot be null
Reassignment
Can be reassigned to new address
Cannot be reassigned
Memory Address
Direct access to memory address
No direct memory address access
Dereferencing
Requires explicit dereferencing
Automatic dereferencing
Typical Usage
Complex data structures, low-level programming
Safe aliasing, function arguments
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Pointer and Reference Definitions
Pointer
Can be assigned null.
Ptr = nullptr; // ptr now points to nothing
Reference
Used to pass variables by reference.
Void func(int& ref) {}
Pointer
Supports arithmetic operations.
Ptr++; // points to the next integer
Reference
Acts as an alias for another variable.
Int& ref = var;
Pointer
Used for dynamic memory management.
Ptr = new int[10];
Reference
Binds once to a variable.
Int& ref = var; // ref can't be reassigned
Pointer
Holds the memory address of another variable.
Int* ptr = &var;
Reference
Automatically accesses the referenced value.
Ref = 5; // sets var to 5
Pointer
Uses an indirection operator to access value.
*ptr = 5; // sets the value pointed by ptr to 5
Reference
Cannot be null.
Int& ref = var; // ref always refers to var
Pointer
A long tapered stick or a laser beacon used to call attention to objects, as on a chart or blackboard.
Reference
The act of referring to something
Filed away the article for future reference.
Reference
Significance for a specified matter; relation or relationship
Her speeches have special reference to environmental policy.
FAQs
Can a pointer be null?
Yes, a pointer can be null, indicating it points to nothing.
How is memory accessed with a pointer?
Memory is accessed directly using the address stored in the pointer.
What is a pointer in programming?
A pointer is a variable that stores the address of another variable.
Can a reference be reassigned?
No, once a reference is set to an object, it cannot be changed.
How is memory accessed with a reference?
Memory is accessed indirectly through the alias created by the reference.
Can a reference be null?
No, a reference cannot be null and must reference a valid object.
What is pointer arithmetic?
Pointer arithmetic is performing operations on the address a pointer holds.
Why use pointers?
Pointers are used for dynamic memory management and low-level programming.
How do you initialize a reference?
A reference is initialized by directly associating it with an existing variable.
What is a reference in programming?
A reference is an alias for an already existing variable.
Do references support arithmetic operations?
No, arithmetic operations are not applicable to references.
Can a pointer be reassigned?
Yes, a pointer can be reassigned to point to a different address.
Are pointers safer or references?
References are generally considered safer due to their non-nullability and automatic dereferencing.
Is it possible to have an array of references?
No, you cannot have an array of references.
Can references be used for dynamic memory allocation?
References are not typically used for dynamic memory allocation; pointers are preferred.
What is a null pointer?
A null pointer is a pointer that does not point to any object or address.
How do you initialize a pointer?
A pointer is initialized by assigning it the address of a variable or memory.
How are pointers dereferenced?
Pointers are dereferenced using the '*' operator.
Why use references?
References are used for safer, more readable code when aliasing or passing by reference.
How are references dereferenced?
References are automatically dereferenced; no operator is needed.
About Author
Written by
Janet WhiteJanet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.
Edited by
Aimie CarlsonAimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.
