Why Can't I Directly Assign Arrays in C , and What Are the Alternatives?

Array Assignment Dilemma in C

In C , assigning an array to another array directly is not feasible, and the error message "Error C2106: '=' : left operand must be l-value" is encountered. This issue stems from the peculiar behaviors of arrays in C due to its compatibility with C.

Understanding the Behavior

Arrays in C are not assignable due to an inheritance from C's array implementation. Arrays are represented as decaying references to their first element, making them non-modifiable l-values. In other words, arrays cannot be assigned to other objects like regular variables.

Solution

To work with array-like functionality in C , alternative containers from the Standard Template Library (STL) are recommended, such as std::array or std::vector. These STL containers allow for array-like behavior while providing assignment capabilities.

Example with std::array

#include <array>

int main() {
    std::array<int, 5> numbers = {1, 2, 3};
    std::array<int, 5> values = {};

    values = numbers;
}

Fallback with Arrays

If using STL containers is not an option, copying array elements manually using a loop or a function like std::copy is necessary.

Example with Array Copying

#include <algorithm>

int main() {
    int numbers[5] = {1, 2, 3};
    int values[5] = {};

    std::copy(numbers, numbers + 5, values);
}

Additional Note

The values array can be initialized with an empty initializer list, as shown below, relying on the standard-defined value initialization rule for aggregates, which initializes unspecified elements to zero.

int values[5] = {};

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