Pointer arithmetic in C++ - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is pointer arithmetic in C++?

Pointer arithmetic means adding or subtracting integers to or from pointers to move through memory locations of the pointed data type.

beginner

How does adding 1 to a pointer affect its value?

Adding 1 to a pointer moves it to the next element of its type, not just the next byte. For example, if it points to an int (4 bytes), adding 1 moves it 4 bytes forward.

intermediate

What happens when you subtract two pointers?

Subtracting two pointers gives the number of elements between them, assuming they point to elements of the same array.

beginner

Why can't you add two pointers together?

Adding two pointers is not allowed because it doesn't make sense to combine two memory addresses. Pointer arithmetic only supports adding or subtracting integers to pointers.

beginner

Example: If int* p points to address 1000 and sizeof(int) is 4, what is the address after p + 3?

The address will be 1000 + 3 * 4 = 1012 because pointer arithmetic moves in steps of the size of the pointed type.

What does adding 2 to a pointer of type double* do?

A Moves the pointer forward by 2 bytes

B Moves the pointer forward by 2 times the size of double

C Moves the pointer backward by 2 bytes

D Causes a compilation error

Adding 2 to a double* pointer moves it forward by 2 times the size of double in memory.

What is the result of subtracting two pointers pointing inside the same array?

A The difference in bytes between the two addresses

B Undefined behavior

C The number of elements between the two pointers

D The sum of the two pointers

Subtracting two pointers gives the number of elements between them, not bytes.

Which of the following is NOT allowed in pointer arithmetic?

A Adding two pointers

B Subtracting an integer from a pointer

C Adding an integer to a pointer

D Subtracting two pointers

Adding two pointers is not allowed in C++ pointer arithmetic.

If p is an int* pointing to address 2000 and sizeof(int) is 4, what address does p - 1 point to?

A 2004

B 1999

C 2001

D 1996

Subtracting 1 moves the pointer back by 4 bytes, so 2000 - 4 = 1996.

Why is pointer arithmetic useful?

A To navigate through elements in arrays efficiently

B To perform math on memory addresses directly

C To convert pointers to integers

D To multiply pointers

Pointer arithmetic helps move through array elements by adjusting the pointer by element sizes.

Explain how pointer arithmetic works when adding an integer to a pointer.

Think about how arrays are stored in memory.

Describe what happens when you subtract two pointers pointing to elements in the same array.

Consider how many steps separate the two pointers.