Why Do Parentheses Compile Without Errors in Variable Declarations in C ?

Declaration of Variables in Parentheses in C

The following code raises an interesting question:

<code class="cpp">int main() {
    int(s);
}</code>

Why does the declaration of s within parentheses compile without errors?

Explanation

According to [dcl.meaning] in the C standard:

"In a declaration T D where D has the form ( D1 ), the type of the contained declarator-id is the same as that of the contained declarator-id in the declaration T D1."

Simplified, parentheses do not alter the type of the declared identifier but can affect the binding of complex declarators.

Example

In the provided code, s is a declarator. Therefore, parentheses can be used without modifying its meaning:

<code class="cpp">int(s) // Equivalent to int s</code>

Advanced Example

Parentheses prove especially useful in more complex scenarios:

<code class="cpp">int *a[10]; // a is an array of ten pointers to int.
int(*b)[10]; // b is a pointer to an array of ten ints.</code>

These distinctions are essential for ensuring correct memory allocation and referencing.

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