Pointers and arrays in C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a pointer in C?

A pointer is a variable that stores the memory address of another variable. It allows direct access to memory locations.

beginner

How are arrays and pointers related in C?

The name of an array acts like a pointer to its first element. You can use pointers to access array elements by moving through memory.

intermediate

What does the expression *(arr + i) mean when arr is an array?

It means accessing the element at index i of the array arr. It uses pointer arithmetic to move i positions from the start.

beginner

How do you declare a pointer to an integer in C?

You declare it as int *ptr; where ptr can store the address of an integer variable.

intermediate

What happens if you increment a pointer ptr that points to an integer?

Incrementing ptr moves it to point to the next integer in memory, usually increasing the address by the size of an integer (e.g., 4 bytes).

What does the name of an array represent in C?

A A pointer to the last element

B The address of the first element

C The value of the first element

D The total size of the array

The array name acts as a pointer to the first element's memory address.

Which operator is used to get the value stored at the address a pointer points to?

A * (dereference)

B & (address-of)

C -> (arrow)

D + (addition)

The * operator dereferences a pointer to access the value at the pointed memory location.

If int *p = arr; where arr is an array, what does p + 2 point to?

A The third element

B The first element

C The second element

D An invalid memory location

Pointer arithmetic moves by element size, so p + 2 points to the third element.

What is the output of this code snippet?

int arr[3] = {10, 20, 30};
printf("%d", *(arr + 1));

A 10

B 30

C Garbage value

D 20

*(arr + 1) accesses the second element, which is 20.

Which of the following is a valid way to access the first element of an array arr using pointers?

A *(arr + 0)

B *arr

C All of the above

D arr[0]

All these expressions access the first element of the array.

Explain how pointers and arrays are connected in C and how you can use pointer arithmetic to access array elements.

Think about how the array name works like a pointer and how adding numbers to pointers moves through the array.

Describe what happens in memory when you increment a pointer that points to an integer array.

Consider how memory addresses change when you move from one element to the next.