Do Pointers in C Have a Fixed Size Regardless of the Data Type They Point To?

Understanding Pointer Size in C

The question arises, "Does the size of a pointer depend on the size of the type it points to, or do pointers always maintain a fixed size?" Let's delve into this concept, building on the foundation of the duplicate question.

In C , pointers generally possess a fixed size. In 32-bit executables, they commonly occupy 32 bits. However, exceptions exist, such as in older versions of Windows, where 16-bit and 32-bit pointers had to be differentiated.

Consider the following code snippet:

int x = 10;
int *xPtr = &x;
char y = 'a';
char *yPtr = &y;

std::cout << sizeof(x) << "\n";
std::cout << sizeof(xPtr) << "\n";
std::cout << sizeof(y) << "\n";
std::cout << sizeof(yPtr) << "\n";

In this scenario, the output would be as follows:

• sizeof(x): Outputs the size of the variable x, which is 4 for a 32-bit executable (assuming int is 4 bytes).
• sizeof(xPtr): Outputs the size of the pointer variable xPtr, which typically remains fixed as mentioned earlier, regardless of the type it points to.
• sizeof(y): Outputs the size of the character variable y, which is usually 1 byte for a single character.
• sizeof(yPtr): Similar to xPtr, it outputs the size of the pointer variable yPtr, which is the same as xPtr.

It's important to note that while pointers typically have a consistent size, it's unwise to rely on this assumption in your code. If your program depends on pointers being of a specific size, always verify it explicitly.

Function pointers are a notable exception. Their size can vary depending on the calling convention employed by the specific system or compiler. Refer to the response provided by 'Jens' for further insights on function pointers.

The above is the detailed content of Do Pointers in C Have a Fixed Size Regardless of the Data Type They Point To?. For more information, please follow other related articles on the PHP Chinese website!