Why Do C Array Declarations Require Constant Value Expressions?
Dec 07, 2024 am 03:34 AMArray 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.
The above is the detailed content of Why Do C Array Declarations Require Constant Value Expressions?. For more information, please follow other related articles on the PHP Chinese website!

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