Are Pointer and Reference Parameters Functionally Identical in C ?

Pointer vs. Reference Parameters: A Detailed Examination

Question:

Do pointer parameters (e.g., int foo(bar* p) { ... }) and reference parameters (e.g., int foo(bar& r) { ... }) behave identically in C ?

Answer:

The difference between pointers and references goes beyond their implementation details in the standard. References embody a syntactic sugar concept, essentially creating aliases for variables. This allows compilers to optimize code where pointers would otherwise add complexity.

Functional Equivalence:

Assuming no null pointer concerns, the functions foo(bar* p) and foo(bar& r) are essentially equivalent if the someInt() method is not virtual. Both functions directly access the object's member function through the parameter. If someInt() is virtual, however, the reference-based parameter function (foo(bar& r)) will invoke the correct method based on the actual object's type, while the pointer-based function (foo(bar* p)) will always invoke the base class method.

Assigning to a Reference:

The assignment bar& ref = *ptr_to_bar will not cause any slicing. The reference ref will alias the object pointed to by ptr_to_bar, allowing you to access its members directly.

Additional Differences:

• References cannot be assigned NULL.
• The address of a pointer yields the address of the pointer variable, while the address of a reference yields the address of the referenced variable.
• References cannot be reassigned once initialized.

The above is the detailed content of Are Pointer and Reference Parameters Functionally Identical in C ?. For more information, please follow other related articles on the PHP Chinese website!