Pointers in C

The size of a pointer is dependent on the machine for which the code is compiled. On 64-bit computers it’s 64 bits. It also can be different from size_t size, which can hold the size of the largest object.

It’s not guaranteed by the standard that all pointers are the same size. But on practice they are. It’s guaranteed that char * and void * are the same size, all struct * the same size, all union *, etc.

Casting pointers to unsigned long to do various things with them can cause undefined behavior! Whether unsigned long is the same size as a pointer is machine-dependent. Use uintptr_t instead. ^96aaca

Two pointers:

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int *a, *b;

One pointer, one int:

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int* a, b; // please don't do this

References:

• What is the size of a pointer in C? - Quora
• Are all data pointers the same size in one platform for all data types?
• Printing the Value of a Pointer to an Object
• c++ - What is uintptr_t data type - Stack Overflow

• How many instructions to access pointer in C?