Does the Order of `const` and `int` Matter in C Constant Declarations?

Is the Order of Declaration Important for Constant Declaration in C ?

In C , the order in which the const and int keywords appear in a constant declaration can affect the meaning of the code, particularly when declaring pointers. Consider the following examples:

Constant Variable Declarations:

<code class="cpp">int const x = 3;
const int y = 4;</code>

Both declarations are valid, and both create constant variables named x and y. They are semantically equivalent and behave identically.

Pointer Declarations:

However, when declaring pointers, the order becomes crucial:

<code class="cpp">// Declares a constant pointer to an int
const int *ptr1 = &someInt;

// Declares an int that cannot be changed through the pointer
int * const ptr2 = &someInt;

// Both declarations are valid but not equivalent</code>

In the first declaration, const applies to the pointer itself, indicating that the pointer cannot be reassigned to point to a different variable. In the second declaration, const applies to the object being pointed to, ensuring that the data at that memory location cannot be modified through the pointer.

Summary:

For constant variable declarations, the order of const and int is irrelevant. However, for pointer declarations, the order determines whether the pointer itself or the data it points to is being made constant.

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