Do Pointer Sizes Always Match the Data Types They Point To?

Understanding Pointer Size

In programming, pointers are often used to store memory addresses and reference data in other parts of the program. A common question arises: Does the size of a pointer match the size of the type it points to, or do pointers always have a fixed size?

Fixed Size Pointers

In most cases, pointers have a fixed size, independent of the type they refer to. This fixed size is determined by the architecture of the underlying system. For instance, on a machine with a 32-bit architecture, pointers typically occupy 32 bits of memory, regardless of the size of the data they point to.

Example Implementation

Consider the following C code snippet:

int x = 10;
int * xPtr = &x;  // Pointer to an integer
char y = 'a';
char * yPtr = &y;  // Pointer to a character

If we compile and run this code:

std::cout << sizeof(x) << "\n";  // Size of integer
std::cout << sizeof(xPtr) << "\n";  // Size of integer pointer
std::cout << sizeof(y) << "\n";  // Size of character
std::cout << sizeof(yPtr) << "\n";  // Size of character pointer

The output would likely be:

4
8  // Pointer size on a 64-bit machine
1
8  // Pointer size on a 64-bit machine

As you can see, the size of both pointers (xPtr and yPtr) is the same, even though they point to data of different sizes (integer and character).

Exceptions

While pointers usually have a fixed size, there are some exceptions. For instance, on old 16-bit Windows systems, there were both 16-bit and 32-bit pointers. However, on modern desktop operating systems, it's generally safe to assume that pointers within a given executable have a uniform size.

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