How Are Objects Passed to Functions in C ?

Understanding C Object Passing Mechanisms

In C , the passing of objects to functions can be a topic of confusion. While it's generally understood that basic data types (e.g., integers, floats) are passed by value, there is uncertainty surrounding the passing of objects.

Call by Value vs. Call by Reference

The distinction between call by value and call by reference is crucial. In call by value, a copy of the passed argument is created, while in call by reference, a pointer to the actual argument is passed.

Passing Simple Data Types

Int, float, and other simple data types are universally passed by value. This means that when an object is passed to a function, a copy of it is created and stored in the function's local memory.

Passing Arrays

Arrays are passed differently. Here's why:

• If the function is defined to receive an array by value (e.g., void foo(int arr[])), only a pointer to the first element of the array is passed. This is considered call by value, even though the argument is an array.
• However, it is possible to pass an array by reference by explicitly stating the array's size (e.g., void foo(int (&arr)[10])).

Passing Objects

Similar to arrays, objects are also passed by reference by default. This means that a pointer to the object is passed, not a copy of the object itself. This is because copying an object can be an expensive operation, especially for large objects.

Conclusion

In conclusion, C passes objects by reference unless the function signature explicitly specifies otherwise. By understanding these passing mechanisms, developers can design C functions and applications that efficiently handle data manipulation.

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