Pass by Value or Pass by Reference: How are Pointer Arguments Handled in C ?

Passing Pointer Arguments: Pass by Value or Pass by Reference?

In C , function arguments are typically passed by value, which means a copy of the argument variable is created within the function. This also applies to pointer arguments, so when a pointer is passed to a function, a copy of the pointer variable (not the memory pointed to) is passed.

Therefore, modifications made to the pointer variable within the function, such as changing the address it points to, will not affect the original pointer outside the function. However, changes made to the memory pointed to through the dereferenced pointer, such as modifying the value of the object it references, will be reflected outside the function because the object itself is being referenced, not the pointer.

In cases where you need to modify the pointer value itself within a function, pointer to pointer arguments can be used. By passing a pointer to a pointer, you are essentially passing a reference to the pointer variable. Any changes to the pointer within the function will then be reflected in the original pointer outside the function.

This technique is commonly used in C, where it is known as "pass by reference to pointer." However, in C , the use of references is generally preferred over pointers, as they offer similar functionality with improved syntax and compiler support.

References are essentially aliases to other variables, and when a reference is passed to a function, a reference to the original variable is effectively passed. This means any changes made to the reference within the function will be reflected in the original variable outside the function.

Both pointer to pointer arguments and references can be used to modify pointer values within functions. The choice between the two methods depends on factors such as code complexity, readability, and compiler support.

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