How to Correctly Pass Arrays by Reference in C ?

Passing Arrays by Reference in C

In C , passing arrays as function arguments by reference is commonly accepted to ensure that any modifications made to the array within the function are reflected in the calling code. However, a recent compiler error has raised doubts about this practice.

Why is "void foo(double& bar)" not allowed?

The syntax "void foo(double& bar)" attempts to pass a double array reference to the function foo. However, C does not support this approach. Arrays are primarily passed by reference, not by the individual elements themselves.

Proper Way to Pass an Array by Reference

To correctly pass an array by reference, use the following syntax:

void foo(double (&bar)[10]);

In this example, "bar" represents an array of doubles with 10 elements passed by reference. This ensures that any changes made to "bar" within foo will also occur in the calling code.

Alternative Solutions

Passing an array by reference is often preferred to avoid unnecessary copying and performance issues. However, it's crucial to note that arrays need to be a fixed size when passed by reference. If you require an array of arbitrary size, consider the following alternatives:

• std::vector: Use a vector to store the elements in a flexible array. This allows for dynamic resizing and makes the code less error-prone.
• std::array (C 11 and later): Similar to a vector, std::array provides a fixed-size array. However, it offers additional features such as direct memory access and can be copied efficiently.

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