Why Do C Array Declarations Require Constant Value Expressions?

Array Declarations in C : Understanding Constant Value Expressions

In C , when attempting to create an array based on variable dimensions, such as:

int row = 8;
int col = 8;
int [row][col];

an error like "expression must have a constant value" may arise. This error occurs because the size of an array must be fixed at compile time.

To address this issue, there are two options:

1. Dynamic Array Allocation:

For a dynamically sized array, it is necessary to allocate memory on the heap and manually manage its allocation and deallocation. This can be done as follows:

// Allocate the array
int** arr = new int*[row];
for (int i = 0; i < row; i++) {
    arr[i] = new int[col];
}

// Use the array

// Deallocate the array
for (int i = 0; i < row; i++) {
    delete[] arr[i];
}
delete[] arr;

2. Constants Declared Array:

If the array size is fixed, it can be declared using constants:

const int row = 8;
const int col = 8;
int arr[row][col];

In the first example, the array declaration lacks a variable name, which would cause a separate compilation error. Additionally, the compiler requires constant value expressions for array size declarations to ensure statically known boundaries and optimized resource management.

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