Is C Pointer Argument Passing Truly Pass-by-Value?

Is Passing Pointer Argument Pass by Value in C ?

In C , passing a pointer argument is indeed pass by value. This means that a copy of the pointer variable's contents (the address of the pointed object) is passed to the function.

Any modification made to the value of the pointer within the function body will not affect the original pointer outside the function. However, changes made to the value of the object pointed to are reflected.

Using Pointer to Pointer as Function Argument

To modify the pointer value itself within a function, a pointer to a pointer must be used as an argument. This technique is acceptable and is the standard procedure for such scenarios. By using the & operator before the pointer argument, the address of the pointer is passed.

References vs. Pointers

While using pointers to achieve this behavior is common practice, in C , using references is generally preferred over pointers for several reasons:

• Reduced syntactic complexity in function bodies
• Provision of more information to the compiler

Drawbacks of References

• Break the pass-by-value rule, requiring attention to parameter behavior
• Not supported by C

In the specific case of pointer to pointers, using references simplifies the implementation. It may even be possible to eliminate the pointer levels entirely, passing a single reference instead.

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